523c656e25
Summary:
This patch is an enhancement to propagate dbg.value information when Phis are created on behalf of LCSSA.
I noticed a case where a value carried across a loop was reported as <optimized out>.
Specifically this case:
```
int bar(int x, int y) {
return x + y;
}
int foo(int size) {
int val = 0;
for (int i = 0; i < size; ++i) {
val = bar(val, i); // Both val and i are correct
}
return val; // <optimized out>
}
```
In the above case, after all of the interesting computation completes our value
is reported as "optimized out." This change will add a dbg.value to correct this.
This patch also moves the dbg.value insertion routine from LoopRotation.cpp
into Local.cpp, so that we can share it in both places (LoopRotation and LCSSA).
Reviewers: mzolotukhin, aprantl, vsk, davide
Reviewed By: aprantl, vsk
Subscribers: dberlin, llvm-commits
Differential Revision: https://reviews.llvm.org/D42551
llvm-svn: 325926
28 lines
942 B
LLVM
28 lines
942 B
LLVM
; RUN: opt < %s -lcssa -S | FileCheck %s
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; RUN: opt < %s -passes=lcssa -S | FileCheck %s
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; RUN: opt < %s -debugify -lcssa -S | FileCheck -check-prefix=CHECK2 %s
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define void @lcssa(i1 %S2) {
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; CHECK-LABEL: @lcssa
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entry:
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br label %loop.interior
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loop.interior: ; preds = %post.if, %entry
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br i1 %S2, label %if.true, label %if.false
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if.true: ; preds = %loop.interior
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%X1 = add i32 0, 0 ; <i32> [#uses=1]
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br label %post.if
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if.false: ; preds = %loop.interior
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%X2 = add i32 0, 1 ; <i32> [#uses=1]
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br label %post.if
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post.if: ; preds = %if.false, %if.true
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%X3 = phi i32 [ %X1, %if.true ], [ %X2, %if.false ] ; <i32> [#uses=1]
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br i1 %S2, label %loop.exit, label %loop.interior
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loop.exit: ; preds = %post.if
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; CHECK: %X3.lcssa = phi i32
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; CHECK2: call void @llvm.dbg.value(metadata i32 %X3.lcssa, metadata !11, metadata !DIExpression()), !dbg !19
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; CHECK: %X4 = add i32 3, %X3.lcssa
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%X4 = add i32 3, %X3 ; <i32> [#uses=0]
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ret void
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}
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