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Fix SROA with a PHI mergig values from a same block

This fixes the bug 47945. It is legal to have a PHI with values
from from the same block, but values must stay the same. In this
case it is illegal to merge different values.

Differential Revision: https://reviews.llvm.org/D89978
This commit is contained in:
Stanislav Mekhanoshin 2020-10-22 11:14:35 -07:00
parent ec700eefc9
commit b2232cc171
2 changed files with 82 additions and 6 deletions

View File

@ -3545,13 +3545,20 @@ private:
PHI->getNumIncomingValues(),
PHI->getName() + ".sroa.phi");
for (unsigned I = 0, E = PHI->getNumIncomingValues(); I != E; ++I) {
Instruction *In = cast<Instruction>(PHI->getIncomingValue(I));
BasicBlock *B = PHI->getIncomingBlock(I);
Value *NewVal = nullptr;
int Idx = NewPN->getBasicBlockIndex(B);
if (Idx >= 0) {
NewVal = NewPN->getIncomingValue(Idx);
} else {
Instruction *In = cast<Instruction>(PHI->getIncomingValue(I));
IRBuilderTy B(In->getParent(), std::next(In->getIterator()));
Value *NewVal = IsInBounds
? B.CreateInBoundsGEP(In, Index, In->getName() + ".sroa.gep")
: B.CreateGEP(In, Index, In->getName() + ".sroa.gep");
NewPN->addIncoming(NewVal, PHI->getIncomingBlock(I));
IRBuilderTy B(In->getParent(), std::next(In->getIterator()));
NewVal = IsInBounds
? B.CreateInBoundsGEP(In, Index, In->getName() + ".sroa.gep")
: B.CreateGEP(In, Index, In->getName() + ".sroa.gep");
}
NewPN->addIncoming(NewVal, B);
}
Visited.erase(&GEPI);

View File

@ -452,6 +452,75 @@ bb2:
ret void
}
define void @constant_value_phi() {
; CHECK-LABEL: @constant_value_phi(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[LAND_LHS_TRUE_I:%.*]]
; CHECK: land.lhs.true.i:
; CHECK-NEXT: br i1 undef, label [[COND_END_I:%.*]], label [[COND_END_I]]
; CHECK: cond.end.i:
; CHECK-NEXT: unreachable
;
entry:
%s1 = alloca [3 x i16]
%s = alloca [3 x i16]
%cast = bitcast [3 x i16]* %s1 to i16*
br label %land.lhs.true.i
land.lhs.true.i: ; preds = %entry
br i1 undef, label %cond.end.i, label %cond.end.i
cond.end.i: ; preds = %land.lhs.true.i, %land.lhs.true.i
%.pre-phi1 = phi i16* [ %cast, %land.lhs.true.i ], [ %cast, %land.lhs.true.i ]
%cast2 = bitcast [3 x i16]* %s to i16*
call void @llvm.memcpy.p0i16.p0i16.i64(i16* %.pre-phi1, i16* %cast2, i64 3, i1 false)
%gep = getelementptr inbounds [3 x i16], [3 x i16]* %s, i32 0, i32 0
%load = load i16, i16* %gep
unreachable
}
define i32 @test_sroa_phi_gep_multiple_values_from_same_block(i32 %arg) {
; CHECK-LABEL: @test_sroa_phi_gep_multiple_values_from_same_block(
; CHECK-NEXT: bb.1:
; CHECK-NEXT: switch i32 [[ARG:%.*]], label [[BB_3:%.*]] [
; CHECK-NEXT: i32 1, label [[BB_2:%.*]]
; CHECK-NEXT: i32 2, label [[BB_2]]
; CHECK-NEXT: i32 3, label [[BB_4:%.*]]
; CHECK-NEXT: i32 4, label [[BB_4]]
; CHECK-NEXT: ]
; CHECK: bb.2:
; CHECK-NEXT: br label [[BB_4]]
; CHECK: bb.3:
; CHECK-NEXT: br label [[BB_4]]
; CHECK: bb.4:
; CHECK-NEXT: [[PHI_SROA_PHI_SROA_SPECULATED:%.*]] = phi i32 [ undef, [[BB_3]] ], [ undef, [[BB_2]] ], [ undef, [[BB_1:%.*]] ], [ undef, [[BB_1]] ]
; CHECK-NEXT: ret i32 [[PHI_SROA_PHI_SROA_SPECULATED]]
;
bb.1:
%a = alloca %pair, align 4
%b = alloca %pair, align 4
switch i32 %arg, label %bb.3 [
i32 1, label %bb.2
i32 2, label %bb.2
i32 3, label %bb.4
i32 4, label %bb.4
]
bb.2: ; preds = %bb.1, %bb.1
br label %bb.4
bb.3: ; preds = %bb.1
br label %bb.4
bb.4: ; preds = %bb.1, %bb.1, %bb.3, %bb.2
%phi = phi %pair* [ %a, %bb.3 ], [ %a, %bb.2 ], [ %b, %bb.1 ], [ %b, %bb.1 ]
%gep = getelementptr inbounds %pair, %pair* %phi, i32 0, i32 1
%load = load i32, i32* %gep, align 4
ret i32 %load
}
declare %pair* @foo()
declare i32 @__gxx_personality_v0(...)
declare void @llvm.memcpy.p0i16.p0i16.i64(i16* noalias nocapture writeonly, i16* noalias nocapture readonly, i64, i1 immarg)