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[SCCP] Use constant ranges for PHI nodes.
For PHIs with multiple incoming values, we can improve precision by using constant ranges for integers. We can over-approximate phis by merging the incoming values. Reviewers: davide, efriedma, mssimpso Reviewed By: efriedma Differential Revision: https://reviews.llvm.org/D71933
This commit is contained in:
Florian Hahn
parent
9373d5a9bf
commit
e306a84b0e
@ -739,9 +739,8 @@ void SCCPSolver::visitPHINode(PHINode &PN) {
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if (PN.getType()->isStructTy())
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return (void)markOverdefined(&PN);
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if (isOverdefined(getValueState(&PN))) {
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return (void)markOverdefined(&PN);
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}
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if (getValueState(&PN).isOverdefined())
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return; // Quick exit
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// Super-extra-high-degree PHI nodes are unlikely to ever be marked constant,
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// and slow us down a lot. Just mark them overdefined.
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@ -753,38 +752,19 @@ void SCCPSolver::visitPHINode(PHINode &PN) {
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// constant, and they agree with each other, the PHI becomes the identical
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// constant. If they are constant and don't agree, the PHI is overdefined.
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// If there are no executable operands, the PHI remains unknown.
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Constant *OperandVal = nullptr;
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bool Changed = false;
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for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
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LatticeVal IV = getValueState(PN.getIncomingValue(i));
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if (IV.isUnknownOrUndef()) continue; // Doesn't influence PHI node.
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if (!isEdgeFeasible(PN.getIncomingBlock(i), PN.getParent()))
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continue;
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if (isOverdefined(IV)) // PHI node becomes overdefined!
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return (void)markOverdefined(&PN);
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if (!OperandVal) { // Grab the first value.
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OperandVal = getConstant(IV);
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continue;
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}
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// There is already a reachable operand. If we conflict with it,
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// then the PHI node becomes overdefined. If we agree with it, we
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// can continue on.
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// Check to see if there are two different constants merging, if so, the PHI
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// node is overdefined.
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if (getConstant(IV) != OperandVal)
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return (void)markOverdefined(&PN);
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LatticeVal &Res = getValueState(&PN);
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Changed |= Res.mergeIn(IV, DL);
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if (Res.isOverdefined())
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break;
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}
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// If we exited the loop, this means that the PHI node only has constant
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// arguments that agree with each other(and OperandVal is the constant) or
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// OperandVal is null because there are no defined incoming arguments. If
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// this is the case, the PHI remains unknown.
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if (OperandVal)
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markConstant(&PN, OperandVal); // Acquire operand value
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if (Changed)
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pushToWorkListMsg(ValueState[&PN], &PN);
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}
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void SCCPSolver::visitReturnInst(ReturnInst &I) {
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@ -44,8 +44,7 @@ define void @sdiv1_cmp_range_1(i32 %x, i1 %c) {
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; CHECK: bb3:
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; CHECK-NEXT: [[P:%.*]] = phi i32 [ 1, [[BB1]] ], [ 2, [[BB2]] ]
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; CHECK-NEXT: [[D:%.*]] = sdiv i32 1, [[X:%.*]]
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; CHECK-NEXT: [[C_0:%.*]] = icmp slt i32 [[P]], [[D]]
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; CHECK-NEXT: call void @use(i1 [[C_0]])
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; CHECK-NEXT: call void @use(i1 false)
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; CHECK-NEXT: [[C_1:%.*]] = icmp eq i32 [[P]], [[D]]
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; CHECK-NEXT: call void @use(i1 [[C_1]])
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; CHECK-NEXT: ret void
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@ -77,10 +76,8 @@ define void @sdiv1_cmp_range_2(i32 %x, i1 %c) {
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; CHECK: bb3:
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; CHECK-NEXT: [[P:%.*]] = phi i32 [ 3, [[BB1]] ], [ 2, [[BB2]] ]
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; CHECK-NEXT: [[D:%.*]] = sdiv i32 1, [[X:%.*]]
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; CHECK-NEXT: [[C_0:%.*]] = icmp slt i32 [[P]], [[D]]
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; CHECK-NEXT: call void @use(i1 [[C_0]])
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; CHECK-NEXT: [[C_1:%.*]] = icmp eq i32 [[P]], [[D]]
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; CHECK-NEXT: call void @use(i1 [[C_1]])
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; CHECK-NEXT: call void @use(i1 false)
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; CHECK-NEXT: call void @use(i1 false)
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; CHECK-NEXT: ret void
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;
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br i1 %c, label %bb1, label %bb2
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@ -59,12 +59,9 @@ entry:
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ret i32 %res.2
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}
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; x is overdefined, because constant ranges are only used for parameter
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; values.
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; CHECK-LABEL: f3
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; CHECK: %cmp = icmp sgt i32 %x, 300
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; CHECK: %res = select i1 %cmp, i32 1, i32 2
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; CHECK: ret i32 %res
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; CHECK-LABEL: entry:
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; CHECK: ret i32 undef
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define internal i32 @f3(i32 %x) {
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entry:
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%cmp = icmp sgt i32 %x, 300
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@ -83,7 +80,7 @@ if.true:
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end:
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%res = phi i32 [ 0, %entry], [ 1, %if.true ]
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%call1 = tail call i32 @f3(i32 %res)
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ret i32 %call1
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ret i32 2
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}
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; CHECK-LABEL: f4
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215
test/Transforms/SCCP/ip-ranges-phis.ll
Normal file
215
test/Transforms/SCCP/ip-ranges-phis.ll
Normal file
@ -0,0 +1,215 @@
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; RUN: opt < %s -ipsccp -S | FileCheck %s
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define internal i32 @f1(i32 %x) {
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; CHECK-LABEL: define internal i32 @f1(
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; CHECK-NEXT: ret i32 undef
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;
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%cmp = icmp sgt i32 %x, 300
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%res = select i1 %cmp, i32 1, i32 2
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ret i32 %res
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}
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; %res is a constant range [0, 2) from a PHI node.
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define i32 @caller1(i1 %cmp) {
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; CHECK-LABEL: define i32 @caller1(
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; CHECK-LABEL: entry:
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; CHECK-NEXT: br i1 %cmp, label %if.true, label %end
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; CHECK-LABEL: if.true:
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; CHECK-NEXT: br label %end
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; CHECK-LABEL: end:
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; CHECK-NEXT: %res = phi i32 [ 0, %entry ], [ 1, %if.true ]
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; CHECK-NEXT: %call1 = tail call i32 @f1(i32 %res)
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; CHECK-NEXT: ret i32 2
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;
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entry:
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br i1 %cmp, label %if.true, label %end
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if.true:
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br label %end
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end:
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%res = phi i32 [ 0, %entry], [ 1, %if.true ]
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%call1 = tail call i32 @f1(i32 %res)
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ret i32 %call1
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}
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define internal i32 @f2(i32 %x, i32 %y, i32 %z, i1 %cmp.1, i1 %cmp.2) {
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; CHECK-LABEL: define internal i32 @f2(
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; CHECK-LABEL: entry:
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; CHECK-NEXT: br i1 %cmp.1, label %if.true.1, label %end
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; CHECK-LABEL: if.true.1:
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; CHECK-NEXT: br i1 %cmp.2, label %if.true.2, label %end
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; CHECK-LABEL: if.true.2:
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; CHECK-NEXT: br label %end
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; CHECK-LABEL: end:
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; CHECK-NEXT: %p = phi i32 [ %x, %entry ], [ %y, %if.true.1 ], [ %z, %if.true.2 ]
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; CHECK-NEXT: %c.1 = icmp sgt i32 %p, 5
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; CHECK-NEXT: %c.2 = icmp eq i32 %p, 0
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; CHECK-NEXT: %c.3 = icmp slt i32 %p, 0
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; CHECK-NEXT: %v.1 = select i1 %c.1, i32 10, i32 100
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; CHECK-NEXT: %v.2 = select i1 %c.2, i32 20, i32 200
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; CHECK-NEXT: %v.3 = select i1 %c.3, i32 30, i32 300
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; CHECK-NEXT: %r.1 = add i32 %v.1, %v.2
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; CHECK-NEXT: %r.2 = add i32 %r.1, %v.3
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; CHECK-NEXT: %r.3 = add i32 %r.2, 400
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; CHECK-NEXT: %r.4 = add i32 %r.3, 50
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; CHECK-NEXT: %r.5 = add i32 %r.4, 60
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; CHECK-NEXT: %r.6 = add i32 %r.4, 700
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; CHECK-NEXT: ret i32 %r.6
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;
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entry:
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br i1 %cmp.1, label %if.true.1, label %end
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if.true.1:
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br i1 %cmp.2, label %if.true.2, label %end
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if.true.2:
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br label %end
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end:
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%p = phi i32 [ %x, %entry ], [ %y, %if.true.1 ], [ %z, %if.true.2 ]
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%c.1 = icmp sgt i32 %p, 5
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%c.2 = icmp eq i32 %p, 0
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%c.3 = icmp slt i32 %p, 0
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%c.4 = icmp sgt i32 %p, 10
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%c.5 = icmp sle i32 %p, 10
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%c.6 = icmp sgt i32 %p, -11
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%c.7 = icmp slt i32 %p, -11
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%v.1 = select i1 %c.1, i32 10, i32 100
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%v.2 = select i1 %c.2, i32 20, i32 200
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%v.3 = select i1 %c.3, i32 30, i32 300
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%v.4 = select i1 %c.4, i32 40, i32 400
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%v.5 = select i1 %c.5, i32 50, i32 500
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%v.6 = select i1 %c.6, i32 60, i32 600
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%v.7 = select i1 %c.7, i32 70, i32 700
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%r.1 = add i32 %v.1, %v.2
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%r.2 = add i32 %r.1, %v.3
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%r.3 = add i32 %r.2, %v.4
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%r.4 = add i32 %r.3, %v.5
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%r.5 = add i32 %r.4, %v.6
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%r.6 = add i32 %r.4, %v.7
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ret i32 %r.6
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}
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define i32 @caller2(i1 %cmp.1, i1 %cmp.2) {
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; CHECK-LABEL: define i32 @caller2(i1 %cmp.1, i1 %cmp.2) {
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; CHECK-LABEL: entry:
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; CHECK-NEXT: br i1 %cmp.1, label %if.true, label %end
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; CHECK-LABEL: if.true: ; preds = %entry
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; CHECK-NEXT: br label %end
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; CHECK-LABEL: end: ; preds = %if.true, %entry
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; CHECK-NEXT: %p1 = phi i32 [ 0, %entry ], [ 1, %if.true ]
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; CHECK-NEXT: %p2 = phi i32 [ 1, %entry ], [ -10, %if.true ]
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; CHECK-NEXT: %p3 = phi i32 [ 1, %entry ], [ 10, %if.true ]
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; CHECK-NEXT: %call1 = tail call i32 @f2(i32 %p1, i32 %p2, i32 %p3, i1 %cmp.1, i1 %cmp.2)
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; CHECK-NEXT: ret i32 %call1
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;
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entry:
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br i1 %cmp.1, label %if.true, label %end
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if.true:
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br label %end
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end:
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%p1 = phi i32 [ 0, %entry], [ 1, %if.true ]
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%p2 = phi i32 [ 1, %entry], [ -10, %if.true ]
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%p3 = phi i32 [ 1, %entry], [ 10, %if.true ]
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%call1 = tail call i32 @f2(i32 %p1, i32 %p2, i32 %p3, i1 %cmp.1, i1 %cmp.2)
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ret i32 %call1
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}
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define internal i32 @f3(i32 %x, i32 %y, i1 %cmp.1) {
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; CHECK-LABEL: define internal i32 @f3(i32 %x, i32 %y, i1 %cmp.1) {
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; CHECK-LABEL: entry:
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; CHECK-NEXT: br i1 %cmp.1, label %if.true.1, label %end
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; CHECK-LABEL: if.true.1: ; preds = %entry
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; CHECK-NEXT: br label %end
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; CHECK-LABEL: end: ; preds = %if.true.1, %entry
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; CHECK-NEXT: %p = phi i32 [ %x, %entry ], [ %y, %if.true.1 ]
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; CHECK-NEXT: %c.1 = icmp sgt i32 %p, 5
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; CHECK-NEXT: %c.2 = icmp eq i32 %p, 0
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; CHECK-NEXT: %c.3 = icmp slt i32 %p, 0
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; CHECK-NEXT: %c.4 = icmp sgt i32 %p, 10
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; CHECK-NEXT: %c.5 = icmp sle i32 %p, 10
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; CHECK-NEXT: %c.6 = icmp sgt i32 %p, -11
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; CHECK-NEXT: %c.7 = icmp slt i32 %p, -11
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; CHECK-NEXT: %v.1 = select i1 %c.1, i32 10, i32 100
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; CHECK-NEXT: %v.2 = select i1 %c.2, i32 20, i32 200
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; CHECK-NEXT: %v.3 = select i1 %c.3, i32 30, i32 300
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; CHECK-NEXT: %v.4 = select i1 %c.4, i32 40, i32 400
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; CHECK-NEXT: %v.5 = select i1 %c.5, i32 50, i32 500
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; CHECK-NEXT: %v.6 = select i1 %c.6, i32 60, i32 600
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; CHECK-NEXT: %v.7 = select i1 %c.7, i32 70, i32 700
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; CHECK-NEXT: %r.1 = add i32 %v.1, %v.2
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; CHECK-NEXT: %r.2 = add i32 %r.1, %v.3
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; CHECK-NEXT: %r.3 = add i32 %r.2, %v.4
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; CHECK-NEXT: %r.4 = add i32 %r.3, %v.5
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; CHECK-NEXT: %r.5 = add i32 %r.4, %v.6
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; CHECK-NEXT: %r.6 = add i32 %r.4, %v.7
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; CHECK-NEXT: ret i32 %r.6
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;
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entry:
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br i1 %cmp.1, label %if.true.1, label %end
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if.true.1:
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br label %end
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end:
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%p = phi i32 [ %x, %entry ], [ %y, %if.true.1 ]
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%c.1 = icmp sgt i32 %p, 5
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%c.2 = icmp eq i32 %p, 0
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%c.3 = icmp slt i32 %p, 0
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%c.4 = icmp sgt i32 %p, 10
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%c.5 = icmp sle i32 %p, 10
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%c.6 = icmp sgt i32 %p, -11
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%c.7 = icmp slt i32 %p, -11
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%v.1 = select i1 %c.1, i32 10, i32 100
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%v.2 = select i1 %c.2, i32 20, i32 200
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%v.3 = select i1 %c.3, i32 30, i32 300
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%v.4 = select i1 %c.4, i32 40, i32 400
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%v.5 = select i1 %c.5, i32 50, i32 500
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%v.6 = select i1 %c.6, i32 60, i32 600
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%v.7 = select i1 %c.7, i32 70, i32 700
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%r.1 = add i32 %v.1, %v.2
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%r.2 = add i32 %r.1, %v.3
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%r.3 = add i32 %r.2, %v.4
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%r.4 = add i32 %r.3, %v.5
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%r.5 = add i32 %r.4, %v.6
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%r.6 = add i32 %r.4, %v.7
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ret i32 %r.6
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}
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define i32 @caller3(i32 %y, i1 %cmp.1) {
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; CHECK-LABEL: define i32 @caller3(i32 %y, i1 %cmp.1) {
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; CHECK-LABEL: entry:
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; CHECK-NEXT: br i1 %cmp.1, label %if.true, label %end
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; CHECK-LABEL: if.true:
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; CHECK-NEXT: br label %end
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; CHECK-LABEL: end:
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; CHECK-NEXT: %p1 = phi i32 [ 0, %entry ], [ 5, %if.true ]
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; CHECK-NEXT: %call1 = tail call i32 @f3(i32 %p1, i32 %y, i1 %cmp.1)
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; CHECK-NEXT: ret i32 %call1
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;
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entry:
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br i1 %cmp.1, label %if.true, label %end
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if.true:
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br label %end
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end:
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%p1 = phi i32 [ 0, %entry], [ 5, %if.true ]
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%call1 = tail call i32 @f3(i32 %p1, i32 %y, i1 %cmp.1)
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ret i32 %call1
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}
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81
test/Transforms/SCCP/phis.ll
Normal file
81
test/Transforms/SCCP/phis.ll
Normal file
@ -0,0 +1,81 @@
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; RUN: opt < %s -sccp -S | FileCheck %s
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define i1 @float.1(i1 %cmp) {
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; CHECK-LABEL: define i1 @float.1(i1 %cmp) {
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; CHECK-LABEL: end:
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; CHECK-NEXT: ret i1 true
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;
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entry:
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br i1 %cmp, label %if.true, label %end
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if.true:
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br label %end
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end:
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%p = phi float [ 1.0, %entry ], [ 1.0, %if.true]
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%c = fcmp ueq float %p, 1.0
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ret i1 %c
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}
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define i1 @float.2(i1 %cmp) {
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; CHECK-LABEL: define i1 @float.2(i1 %cmp) {
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; CHECK-LABEL: end:
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; CHECK-NEXT: %p = phi float [ 1.000000e+00, %entry ], [ 2.000000e+00, %if.true ]
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; CHECK-NEXT: %c = fcmp ueq float %p, 1.000000e+00
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; CHECK-NEXT: ret i1 %c
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;
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entry:
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br i1 %cmp, label %if.true, label %end
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if.true:
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br label %end
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end:
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%p = phi float [ 1.0, %entry ], [ 2.0, %if.true]
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%c = fcmp ueq float %p, 1.0
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ret i1 %c
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}
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define i1 @float.3(float %f, i1 %cmp) {
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; CHECK-LABEL: define i1 @float.3(float %f, i1 %cmp)
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; CHECK-LABEL: end:
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; CHECK-NEXT: %p = phi float [ 1.000000e+00, %entry ], [ %f, %if.true ]
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; CHECK-NEXT: %c = fcmp ueq float %p, 1.000000e+00
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; CHECK-NEXT: ret i1 %c
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;
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entry:
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br i1 %cmp, label %if.true, label %end
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||||
if.true:
|
||||
br label %end
|
||||
|
||||
end:
|
||||
%p = phi float [ 1.0, %entry ], [ %f, %if.true]
|
||||
%c = fcmp ueq float %p, 1.0
|
||||
ret i1 %c
|
||||
}
|
||||
|
||||
|
||||
define i1 @float.4_unreachable(float %f, i1 %cmp) {
|
||||
; CHECK-LABEL: define i1 @float.4_unreachable(float %f, i1 %cmp)
|
||||
|
||||
; CHECK-LABEL: end:
|
||||
; CHECK-NEXT: ret i1 false
|
||||
;
|
||||
entry:
|
||||
br i1 %cmp, label %if.true, label %end
|
||||
|
||||
if.true:
|
||||
br label %end
|
||||
|
||||
dead:
|
||||
br label %end
|
||||
|
||||
end:
|
||||
%p = phi float [ 1.0, %entry ], [ 1.0, %if.true], [ %f, %dead ]
|
||||
%c = fcmp une float %p, 1.0
|
||||
ret i1 %c
|
||||
}
|
||||
@ -141,8 +141,7 @@ define i1 @constant_range_and_255_100(i1 %cond, i64 %a) {
|
||||
; CHECK: bb3:
|
||||
; CHECK-NEXT: [[P:%.*]] = phi i64 [ [[R_1]], [[BB1]] ], [ [[R_2]], [[BB2]] ]
|
||||
; CHECK-NEXT: [[P_AND:%.*]] = and i64 [[P]], 512
|
||||
; CHECK-NEXT: [[C:%.*]] = icmp ult i64 [[P_AND]], 256
|
||||
; CHECK-NEXT: ret i1 [[C]]
|
||||
; CHECK-NEXT: ret i1 true
|
||||
;
|
||||
entry:
|
||||
br i1 %cond, label %bb1, label %bb2
|
||||
|
||||
Loading…
Reference in New Issue
Block a user