forked from OSchip/llvm-project
[NewGVN] FIx phi-of-ops in the presence of memory read operations
The phi-of-ops functionality has a function OpIsSafeForPHIOfOps to determine when it's safe to create the new phi. But this function only checks for the obvious dominator conditions and ignores memory. This patch takes the conservative approach and disables phi-of-ops whenever there's a load that doesn't dominate the phi, as its value may be affected by a store inside the loop. This can be improved later to check aliasing between the load/stores. Fixes https://llvm.org/PR53277 Reviewed By: asbirlea Differential Revision: https://reviews.llvm.org/D117999
This commit is contained in:
Nuno Lopes
parent
66c602be25
commit
24a49e99f3
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@ -2587,6 +2587,15 @@ bool NewGVN::OpIsSafeForPHIOfOpsHelper(
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}
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auto *OrigI = cast<Instruction>(V);
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// When we hit an instruction that reads memory (load, call, etc), we must
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// consider any store that may happen in the loop. For now, we assume the
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// worst: there is a store in the loop that alias with this read.
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// The case where the load is outside the loop is already covered by the
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// dominator check above.
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// TODO: relax this condition
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if (OrigI->mayReadFromMemory())
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return false;
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for (auto *Op : OrigI->operand_values()) {
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if (!isa<Instruction>(Op))
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continue;
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@ -1,17 +1,55 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -passes=newgvn -enable-phi-of-ops=true -S -o - %s | FileCheck %s
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define void @hoisted-load(i8* %p, i8* %q) {
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; CHECK-LABEL: @hoisted-load(
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; CHECK-NEXT: bb56:
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; CHECK-NEXT: [[N60:%.*]] = load i8, i8* [[P:%.*]], align 1
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; CHECK-NEXT: br label [[BB57:%.*]]
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; CHECK: bb57:
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; CHECK-NEXT: [[PHIOFOPS:%.*]] = phi i1 [ true, [[BB56:%.*]] ], [ [[N62:%.*]], [[BB229:%.*]] ]
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; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229]] ], [ true, [[BB56]] ]
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; CHECK-NEXT: [[IDX:%.*]] = phi i8 [ 0, [[BB56]] ], [ [[INC:%.*]], [[BB229]] ]
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; CHECK-NEXT: [[N62]] = icmp ne i8 [[N60]], 2
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; CHECK-NEXT: br i1 [[PHIOFOPS]], label [[BB229]], label [[BB237:%.*]]
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; CHECK: bb229:
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; CHECK-NEXT: [[INC]] = add i8 [[IDX]], 1
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; CHECK-NEXT: store i8 [[INC]], i8* [[Q:%.*]], align 1
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; CHECK-NEXT: br label [[BB57]]
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; CHECK: bb237:
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; CHECK-NEXT: ret void
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;
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bb56:
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%n60 = load i8, i8* %p
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br label %bb57
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bb57:
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%n59 = phi i1 [ false, %bb229 ], [ true, %bb56 ]
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%idx = phi i8 [0, %bb56], [%inc, %bb229]
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%n62 = icmp ne i8 %n60, 2
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%n63 = or i1 %n59, %n62
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br i1 %n63, label %bb229, label %bb237
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bb229:
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%inc = add i8 %idx, 1
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store i8 %inc, i8* %q
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br label %bb57
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bb237:
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ret void
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}
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define void @store-in-loop(i8* %p, i8* %q) {
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; CHECK-LABEL: @store-in-loop(
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; CHECK-NEXT: bb56:
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; CHECK-NEXT: br label [[BB57:%.*]]
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; CHECK: bb57:
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; CHECK-NEXT: [[PHIOFOPS:%.*]] = phi i1 [ true, [[BB56:%.*]] ], [ [[N62:%.*]], [[BB229:%.*]] ]
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; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229]] ], [ true, [[BB56]] ]
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; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229:%.*]] ], [ true, [[BB56:%.*]] ]
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; CHECK-NEXT: [[IDX:%.*]] = phi i8 [ 0, [[BB56]] ], [ [[INC:%.*]], [[BB229]] ]
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; CHECK-NEXT: [[N60:%.*]] = load i8, i8* [[P:%.*]], align 1
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; CHECK-NEXT: [[N62]] = icmp ne i8 [[N60]], 2
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; CHECK-NEXT: br i1 [[PHIOFOPS]], label [[BB229]], label [[BB237:%.*]]
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; CHECK-NEXT: [[N62:%.*]] = icmp ne i8 [[N60]], 2
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; CHECK-NEXT: [[N63:%.*]] = or i1 [[N59]], [[N62]]
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; CHECK-NEXT: br i1 [[N63]], label [[BB229]], label [[BB237:%.*]]
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; CHECK: bb229:
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; CHECK-NEXT: [[INC]] = add i8 [[IDX]], 1
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; CHECK-NEXT: store i8 [[INC]], i8* [[Q:%.*]], align 1
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@ -39,17 +77,18 @@ bb237:
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ret void
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}
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; TODO: we should support this case
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define void @no-alias-store-in-loop(i8* noalias %p, i8* noalias %q) {
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; CHECK-LABEL: @no-alias-store-in-loop(
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; CHECK-NEXT: bb56:
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; CHECK-NEXT: br label [[BB57:%.*]]
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; CHECK: bb57:
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; CHECK-NEXT: [[PHIOFOPS:%.*]] = phi i1 [ true, [[BB56:%.*]] ], [ [[N62:%.*]], [[BB229:%.*]] ]
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; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229]] ], [ true, [[BB56]] ]
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; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229:%.*]] ], [ true, [[BB56:%.*]] ]
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; CHECK-NEXT: [[IDX:%.*]] = phi i8 [ 0, [[BB56]] ], [ [[INC:%.*]], [[BB229]] ]
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; CHECK-NEXT: [[N60:%.*]] = load i8, i8* [[P:%.*]], align 1
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; CHECK-NEXT: [[N62]] = icmp ne i8 [[N60]], 2
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; CHECK-NEXT: br i1 [[PHIOFOPS]], label [[BB229]], label [[BB237:%.*]]
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; CHECK-NEXT: [[N62:%.*]] = icmp ne i8 [[N60]], 2
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; CHECK-NEXT: [[N63:%.*]] = or i1 [[N59]], [[N62]]
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; CHECK-NEXT: br i1 [[N63]], label [[BB229]], label [[BB237:%.*]]
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; CHECK: bb229:
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; CHECK-NEXT: [[INC]] = add i8 [[IDX]], 1
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; CHECK-NEXT: store i8 [[INC]], i8* [[Q:%.*]], align 1
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@ -82,11 +121,11 @@ define void @function-in-loop(i8* %p) {
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; CHECK-NEXT: bb56:
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; CHECK-NEXT: br label [[BB57:%.*]]
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; CHECK: bb57:
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; CHECK-NEXT: [[PHIOFOPS:%.*]] = phi i1 [ true, [[BB56:%.*]] ], [ [[N62:%.*]], [[BB229:%.*]] ]
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; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229]] ], [ true, [[BB56]] ]
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; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229:%.*]] ], [ true, [[BB56:%.*]] ]
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; CHECK-NEXT: [[N60:%.*]] = load i8, i8* [[P:%.*]], align 1
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; CHECK-NEXT: [[N62]] = icmp ne i8 [[N60]], 2
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; CHECK-NEXT: br i1 [[PHIOFOPS]], label [[BB229]], label [[BB237:%.*]]
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; CHECK-NEXT: [[N62:%.*]] = icmp ne i8 [[N60]], 2
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; CHECK-NEXT: [[N63:%.*]] = or i1 [[N59]], [[N62]]
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; CHECK-NEXT: br i1 [[N63]], label [[BB229]], label [[BB237:%.*]]
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; CHECK: bb229:
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; CHECK-NEXT: call void @f()
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; CHECK-NEXT: br label [[BB57]]
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@ -111,16 +150,17 @@ bb237:
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ret void
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}
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; TODO: we should support this case
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define void @nowrite-function-in-loop(i8* %p) {
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; CHECK-LABEL: @nowrite-function-in-loop(
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; CHECK-NEXT: bb56:
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; CHECK-NEXT: br label [[BB57:%.*]]
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; CHECK: bb57:
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; CHECK-NEXT: [[PHIOFOPS:%.*]] = phi i1 [ true, [[BB56:%.*]] ], [ [[N62:%.*]], [[BB229:%.*]] ]
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; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229]] ], [ true, [[BB56]] ]
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; CHECK-NEXT: [[N59:%.*]] = phi i1 [ false, [[BB229:%.*]] ], [ true, [[BB56:%.*]] ]
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; CHECK-NEXT: [[N60:%.*]] = load i8, i8* [[P:%.*]], align 1
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; CHECK-NEXT: [[N62]] = icmp ne i8 [[N60]], 2
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; CHECK-NEXT: br i1 [[PHIOFOPS]], label [[BB229]], label [[BB237:%.*]]
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; CHECK-NEXT: [[N62:%.*]] = icmp ne i8 [[N60]], 2
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; CHECK-NEXT: [[N63:%.*]] = or i1 [[N59]], [[N62]]
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; CHECK-NEXT: br i1 [[N63]], label [[BB229]], label [[BB237:%.*]]
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; CHECK: bb229:
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; CHECK-NEXT: call void @f() #[[ATTR0:[0-9]+]]
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; CHECK-NEXT: br label [[BB57]]
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@ -12,12 +12,16 @@ define i32 @foo(i32*, i32) {
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; CHECK-NEXT: store i32 5, i32* [[TMP0:%.*]], align 4
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; CHECK-NEXT: [[TMP3:%.*]] = icmp ne i32 [[TMP1:%.*]], 0
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; CHECK-NEXT: br i1 [[TMP3]], label [[TMP4:%.*]], label [[TMP5:%.*]]
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; CHECK: br label [[TMP5]]
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; CHECK: [[PHIOFOPS:%.*]] = phi i32 [ 10, [[TMP2:%.*]] ], [ 15, [[TMP4]] ]
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; CHECK-NEXT: [[DOT0:%.*]] = phi i32 [ 10, [[TMP4]] ], [ 5, [[TMP2]] ]
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; CHECK-NEXT: br i1 [[TMP3]], label [[TMP6:%.*]], label [[TMP7:%.*]]
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; CHECK: br label [[TMP7]]
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; CHECK: [[DOT1:%.*]] = phi i32 [ [[PHIOFOPS]], [[TMP6]] ], [ [[DOT0]], [[TMP5]] ]
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; CHECK: 4:
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; CHECK-NEXT: br label [[TMP5]]
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; CHECK: 5:
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; CHECK-NEXT: [[DOT0:%.*]] = phi i32 [ 10, [[TMP4]] ], [ 5, [[TMP2:%.*]] ]
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; CHECK-NEXT: br i1 [[TMP3]], label [[TMP6:%.*]], label [[TMP8:%.*]]
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; CHECK: 6:
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; CHECK-NEXT: [[TMP7:%.*]] = add nsw i32 [[DOT0]], 5
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; CHECK-NEXT: br label [[TMP8]]
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; CHECK: 8:
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; CHECK-NEXT: [[DOT1:%.*]] = phi i32 [ [[TMP7]], [[TMP6]] ], [ [[DOT0]], [[TMP5]] ]
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; CHECK-NEXT: ret i32 [[DOT1]]
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;
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store i32 5, i32* %0, align 4
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@ -52,13 +56,18 @@ define i32 @foo2(i32*, i32) {
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; CHECK-NEXT: store i32 5, i32* [[TMP0:%.*]], align 4
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; CHECK-NEXT: [[TMP3:%.*]] = icmp ne i32 [[TMP1:%.*]], 0
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; CHECK-NEXT: br i1 [[TMP3]], label [[TMP4:%.*]], label [[TMP5:%.*]]
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; CHECK: br label [[TMP6:%.*]]
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; CHECK: br label [[TMP6]]
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; CHECK: [[PHIOFOPS:%.*]] = phi i32 [ 10, [[TMP5]] ], [ 15, [[TMP4]] ]
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; CHECK: 4:
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; CHECK-NEXT: br label [[TMP6:%.*]]
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; CHECK: 5:
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; CHECK-NEXT: br label [[TMP6]]
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; CHECK: 6:
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; CHECK-NEXT: [[DOT0:%.*]] = phi i32 [ 10, [[TMP4]] ], [ 5, [[TMP5]] ]
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; CHECK-NEXT: br i1 [[TMP3]], label [[TMP7:%.*]], label [[TMP8:%.*]]
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; CHECK: br label [[TMP8]]
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; CHECK: [[DOT1:%.*]] = phi i32 [ [[PHIOFOPS]], [[TMP7]] ], [ [[DOT0]], [[TMP6]] ]
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; CHECK-NEXT: br i1 [[TMP3]], label [[TMP7:%.*]], label [[TMP9:%.*]]
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; CHECK: 7:
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; CHECK-NEXT: [[TMP8:%.*]] = add nsw i32 [[DOT0]], 5
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; CHECK-NEXT: br label [[TMP9]]
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; CHECK: 9:
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; CHECK-NEXT: [[DOT1:%.*]] = phi i32 [ [[TMP8]], [[TMP7]] ], [ [[DOT0]], [[TMP6]] ]
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; CHECK-NEXT: ret i32 [[DOT1]]
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;
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store i32 5, i32* %0, align 4
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