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13c5bb4a2e
Presently, CodeGenPrepare deletes all nearly empty (only phi and branch) basic blocks. This pass can delete loop preheaders which frequently creates critical edges. A preheader can be a convenient place to spill registers to the stack. If the entrance to a loop body is a critical edge, then spills may occur in the loop body rather than immediately before it. This patch protects loop preheaders from deletion in CodeGenPrepare even if they are nearly empty. Since the patch alters the CFG, it affects a large number of test cases. In most cases, the changes are merely cosmetic (basic blocks have different names or instruction orders change slightly). I am somewhat concerned about the test/CodeGen/Mips/brdelayslot.ll test case. If the loop preheader is not deleted, then the MIPS backend does not take advantage of a branch delay slot. Consequently, I would like some close review by a MIPS expert. The patch also partially subsumes D16893 from George Burgess IV. George correctly notes that CodeGenPrepare does not actually preserve the dominator tree. I think the dominator tree was usually not valid when CodeGenPrepare ran, but I am using LoopInfo to mark preheaders, so the dominator tree is now always valid before CodeGenPrepare. Author: Tom Jablin (tjablin) Reviewers: hfinkel george.burgess.iv vkalintiris dsanders kbarton cycheng http://reviews.llvm.org/D16984 llvm-svn: 265397
149 lines
6.6 KiB
LLVM
149 lines
6.6 KiB
LLVM
; RUN: llc < %s -O3 -march=x86-64 -mcpu=core2 | FileCheck %s
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declare i1 @check() nounwind
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declare i1 @foo(i8*, i8*, i8*) nounwind
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; Check that redundant phi elimination ran
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; CHECK: @test
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; CHECK: %while.body.i
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; CHECK: movs
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; CHECK-NOT: movs
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; CHECK: %for.end.i
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define i32 @test(i8* %base) nounwind uwtable ssp {
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entry:
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br label %while.body.lr.ph.i
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while.body.lr.ph.i: ; preds = %cond.true.i
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br label %while.body.i
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while.body.i: ; preds = %cond.true29.i, %while.body.lr.ph.i
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%indvars.iv7.i = phi i64 [ 16, %while.body.lr.ph.i ], [ %indvars.iv.next8.i, %cond.true29.i ]
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%i.05.i = phi i64 [ 0, %while.body.lr.ph.i ], [ %indvars.iv7.i, %cond.true29.i ]
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%sext.i = shl i64 %i.05.i, 32
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%idx.ext.i = ashr exact i64 %sext.i, 32
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%add.ptr.sum.i = add i64 %idx.ext.i, 16
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br label %for.body.i
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for.body.i: ; preds = %for.body.i, %while.body.i
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%indvars.iv.i = phi i64 [ 0, %while.body.i ], [ %indvars.iv.next.i, %for.body.i ]
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%add.ptr.sum = add i64 %add.ptr.sum.i, %indvars.iv.i
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%arrayidx22.i = getelementptr inbounds i8, i8* %base, i64 %add.ptr.sum
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%0 = load i8, i8* %arrayidx22.i, align 1
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%indvars.iv.next.i = add i64 %indvars.iv.i, 1
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%cmp = call i1 @check() nounwind
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br i1 %cmp, label %for.end.i, label %for.body.i
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for.end.i: ; preds = %for.body.i
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%add.ptr.i144 = getelementptr inbounds i8, i8* %base, i64 %add.ptr.sum.i
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%cmp2 = tail call i1 @foo(i8* %add.ptr.i144, i8* %add.ptr.i144, i8* undef) nounwind
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br i1 %cmp2, label %cond.true29.i, label %cond.false35.i
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cond.true29.i: ; preds = %for.end.i
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%indvars.iv.next8.i = add i64 %indvars.iv7.i, 16
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br i1 false, label %exit, label %while.body.i
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cond.false35.i: ; preds = %for.end.i
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unreachable
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exit: ; preds = %cond.true29.i, %cond.true.i
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ret i32 0
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}
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%struct.anon.7.91.199.307.415.475.559.643.751.835.943.1003.1111.1219.1351.1375.1399.1435.1471.1483.1519.1531.1651.1771 = type { i32, i32, i32 }
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@tags = external global [5000 x %struct.anon.7.91.199.307.415.475.559.643.751.835.943.1003.1111.1219.1351.1375.1399.1435.1471.1483.1519.1531.1651.1771], align 16
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; PR11782: SCEVExpander assert
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;
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; Test phi reuse after LSR that requires SCEVExpander to hoist an
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; interesting GEP.
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;
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; CHECK: @test2
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; CHECK: %entry
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; CHECK-NOT: mov
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; CHECK: je
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define void @test2(i32 %n) nounwind uwtable {
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entry:
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br i1 undef, label %while.end, label %for.cond468
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for.cond468: ; preds = %if.then477, %entry
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%indvars.iv1163 = phi i64 [ %indvars.iv.next1164, %if.then477 ], [ 1, %entry ]
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%k.0.in = phi i32* [ %last, %if.then477 ], [ getelementptr inbounds ([5000 x %struct.anon.7.91.199.307.415.475.559.643.751.835.943.1003.1111.1219.1351.1375.1399.1435.1471.1483.1519.1531.1651.1771], [5000 x %struct.anon.7.91.199.307.415.475.559.643.751.835.943.1003.1111.1219.1351.1375.1399.1435.1471.1483.1519.1531.1651.1771]* @tags, i64 0, i64 0, i32 2), %entry ]
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%k.0 = load i32, i32* %k.0.in, align 4
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%0 = trunc i64 %indvars.iv1163 to i32
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%cmp469 = icmp slt i32 %0, %n
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br i1 %cmp469, label %for.body471, label %for.inc498
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for.body471: ; preds = %for.cond468
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%first = getelementptr inbounds [5000 x %struct.anon.7.91.199.307.415.475.559.643.751.835.943.1003.1111.1219.1351.1375.1399.1435.1471.1483.1519.1531.1651.1771], [5000 x %struct.anon.7.91.199.307.415.475.559.643.751.835.943.1003.1111.1219.1351.1375.1399.1435.1471.1483.1519.1531.1651.1771]* @tags, i64 0, i64 %indvars.iv1163, i32 1
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%1 = load i32, i32* %first, align 4
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br i1 undef, label %if.then477, label %for.inc498
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if.then477: ; preds = %for.body471
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%last = getelementptr inbounds [5000 x %struct.anon.7.91.199.307.415.475.559.643.751.835.943.1003.1111.1219.1351.1375.1399.1435.1471.1483.1519.1531.1651.1771], [5000 x %struct.anon.7.91.199.307.415.475.559.643.751.835.943.1003.1111.1219.1351.1375.1399.1435.1471.1483.1519.1531.1651.1771]* @tags, i64 0, i64 %indvars.iv1163, i32 2
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%indvars.iv.next1164 = add i64 %indvars.iv1163, 1
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br label %for.cond468
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for.inc498: ; preds = %for.inc498, %for.body471, %for.cond468
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br label %for.inc498
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while.end: ; preds = %entry
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ret void
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}
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; PR12898: SCEVExpander crash
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; Test redundant phi elimination when the deleted phi's increment is
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; itself a phi.
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;
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; CHECK: @test3
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; CHECK: %for.body3.lr.ph.us.i.loopexit
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; CHECK-NEXT: in Loop: Header
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; CHECK-NEXT: incq
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; CHECK-NEXT: %for.body3.us.i
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; CHECK-NEXT: Inner Loop
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; CHECK: testb
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; CHECK: je
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; CHECK: jmp
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define fastcc void @test3(double* nocapture %u) nounwind uwtable ssp {
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entry:
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br i1 undef, label %meshBB1, label %meshBB5
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for.inc8.us.i: ; preds = %for.body3.us.i
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br i1 undef, label %meshBB1, label %meshBB
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for.body3.us.i: ; preds = %meshBB, %for.body3.lr.ph.us.i
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%indvars.iv.i.SV.phi = phi i64 [ %indvars.iv.next.i, %meshBB ], [ 0, %for.body3.lr.ph.us.i ]
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%storemerge13.us.i.SV.phi = phi i32 [ 0, %meshBB ], [ 0, %for.body3.lr.ph.us.i ]
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%Opq.sa.calc12 = sub i32 undef, 227
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%0 = add nsw i64 %indvars.iv.i.SV.phi, %indvars.iv8.i.SV.phi26
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%1 = trunc i64 %0 to i32
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%mul.i.us.i = mul nsw i32 0, %1
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%arrayidx5.us.i = getelementptr inbounds double, double* %u, i64 %indvars.iv.i.SV.phi
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%2 = load double, double* %arrayidx5.us.i, align 8
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%indvars.iv.next.i = add i64 %indvars.iv.i.SV.phi, 1
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br i1 undef, label %for.inc8.us.i, label %meshBB
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for.body3.lr.ph.us.i: ; preds = %meshBB1, %meshBB
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%indvars.iv8.i.SV.phi26 = phi i64 [ undef, %meshBB1 ], [ %indvars.iv8.i.SV.phi24, %meshBB ]
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%arrayidx.us.i = getelementptr inbounds double, double* undef, i64 %indvars.iv8.i.SV.phi26
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%3 = add i64 %indvars.iv8.i.SV.phi26, 1
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br label %for.body3.us.i
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for.inc8.us.i2: ; preds = %meshBB5
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unreachable
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eval_At_times_u.exit: ; preds = %meshBB5
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ret void
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meshBB: ; preds = %for.body3.us.i, %for.inc8.us.i
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%indvars.iv8.i.SV.phi24 = phi i64 [ undef, %for.body3.us.i ], [ %3, %for.inc8.us.i ]
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%meshStackVariable.phi = phi i32 [ %Opq.sa.calc12, %for.body3.us.i ], [ undef, %for.inc8.us.i ]
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br i1 undef, label %for.body3.lr.ph.us.i, label %for.body3.us.i
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meshBB1: ; preds = %for.inc8.us.i, %entry
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br label %for.body3.lr.ph.us.i
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meshBB5: ; preds = %entry
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br i1 undef, label %eval_At_times_u.exit, label %for.inc8.us.i2
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}
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