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[Debug] Retain both sets of debug intrinsics in HoistThenElseCodeToIf 

When hoisting common code from the "then" and "else" branches of a condition
to before the "if", there is no need to require that debug intrinsics match
before moving them (and merging them).  Instead, we can simply always keep
all debug intrinsics from both sides of the "if".

This fixes PR36410, which describes a problem where as a result of the attempt
to merge debug locations for two debug intrinsics we end up with an invalid
intrinsic, where the scope indicated in the !dbg location no longer matches
the scope of the variable tracked by the intrinsic.

In addition, this has the benefit that we no longer throw away information
that is actually still valid, helping to generate better debug data.

Reviewed By: vsk

Differential Revision: https://reviews.llvm.org/D44312

llvm-svn: 327175
This commit is contained in:
Ulrich Weigand 2018-03-09 21:37:07 +00:00
parent 735817aa1a
commit fa4e63c0d6
2 changed files with 66 additions and 26 deletions
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41
llvm/lib/Transforms/Utils/SimplifyCFG.cpp
View File

@ -1254,23 +1254,23 @@ static bool HoistThenElseCodeToIf(BranchInst *BI,
BasicBlock::iterator BB2_Itr = BB2->begin();
Instruction *I1 = &*BB1_Itr++, *I2 = &*BB2_Itr++;
// Skip debug info if it is not identical.
DbgInfoIntrinsic *DBI1 = dyn_cast<DbgInfoIntrinsic>(I1);
DbgInfoIntrinsic *DBI2 = dyn_cast<DbgInfoIntrinsic>(I2);
if (!DBI1 || !DBI2 || !DBI1->isIdenticalToWhenDefined(DBI2)) {
while (isa<DbgInfoIntrinsic>(I1))
I1 = &*BB1_Itr++;
while (isa<DbgInfoIntrinsic>(I2))
I2 = &*BB2_Itr++;
}
if (isa<PHINode>(I1) || !I1->isIdenticalToWhenDefined(I2) ||
(isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2)))
return false;
BasicBlock *BIParent = BI->getParent();
bool Changed = false;
do {
for (;;) {
// Move over debug info from both sides unchanged.
while (isa<DbgInfoIntrinsic>(I1)) {
BIParent->getInstList().splice(BI->getIterator(), BB1->getInstList(), I1);
I1 = &*BB1_Itr++;
}
while (isa<DbgInfoIntrinsic>(I2)) {
BIParent->getInstList().splice(BI->getIterator(), BB2->getInstList(), I2);
I2 = &*BB2_Itr++;
}
if (isa<PHINode>(I1) || !I1->isIdenticalToWhenDefined(I2))
return Changed;
// If we are hoisting the terminator instruction, don't move one (making a
// broken BB), instead clone it, and remove BI.
if (isa<TerminatorInst>(I1))
@ -1318,18 +1318,7 @@ static bool HoistThenElseCodeToIf(BranchInst *BI,
I1 = &*BB1_Itr++;
I2 = &*BB2_Itr++;
// Skip debug info if it is not identical.
DbgInfoIntrinsic *DBI1 = dyn_cast<DbgInfoIntrinsic>(I1);
DbgInfoIntrinsic *DBI2 = dyn_cast<DbgInfoIntrinsic>(I2);
if (!DBI1 || !DBI2 || !DBI1->isIdenticalToWhenDefined(DBI2)) {
while (isa<DbgInfoIntrinsic>(I1))
I1 = &*BB1_Itr++;
while (isa<DbgInfoIntrinsic>(I2))
I2 = &*BB2_Itr++;
}
} while (I1->isIdenticalToWhenDefined(I2));
return true;
}
HoistTerminator:
// It may not be possible to hoist an invoke.

51
llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue-inlined.ll Normal file
View File

@ -0,0 +1,51 @@
; RUN: opt -simplifycfg -S < %s | FileCheck %s
; Verify that we don't crash due an invalid !dbg location on the hoisted llvm.dbg.value
define i64 @caller(i64* %ptr, i64 %flag) !dbg !10 {
init:
%v9 = icmp eq i64 %flag, 0
br i1 %v9, label %a, label %b
; CHECK: %vala = load i64, i64* %ptr
; CHECK-NEXT: call void @llvm.dbg.value(metadata i64 %vala, metadata [[MD:![0-9]*]]
; CHECK-NEXT: call void @llvm.dbg.value(metadata i64 %vala, metadata [[MD]]
; CHECK-NEXT: %valbmasked = and i64 %vala, 1
a: ; preds = %init
%vala = load i64, i64* %ptr, align 8
call void @llvm.dbg.value(metadata i64 %vala, metadata !8, metadata !DIExpression()), !dbg !12
br label %test.exit
b: ; preds = %init
%valb = load i64, i64* %ptr, align 8
call void @llvm.dbg.value(metadata i64 %valb, metadata !8, metadata !DIExpression()), !dbg !13
%valbmasked = and i64 %valb, 1
br label %test.exit
test.exit: ; preds = %a, %b
%retv = phi i64 [ %vala, %a ], [ %valbmasked, %b ]
ret i64 %retv
}
; Function Attrs: nounwind readnone speculatable
declare void @llvm.dbg.value(metadata, metadata, metadata) #0
attributes #0 = { nounwind readnone speculatable }
!llvm.module.flags = !{!0}
!llvm.dbg.cu = !{!1}
!0 = !{i32 2, !"Debug Info Version", i32 3}
!1 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !2, isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !3)
!2 = !DIFile(filename: "optbug", directory: "")
!3 = !{}
!4 = distinct !DISubprogram(name: "callee", scope: !2, file: !2, line: 1, type: !5, isLocal: false, isDefinition: true, scopeLine: 1, isOptimized: false, unit: !1, variables: !7)
!5 = !DISubroutineType(types: !6)
!6 = !{null}
!7 = !{!8}
!8 = !DILocalVariable(name: "var", scope: !4, file: !2, type: !9)
!9 = !DIBasicType(name: "var_t", size: 64, encoding: DW_ATE_unsigned)
!10 = distinct !DISubprogram(name: "caller", scope: !2, file: !2, line: 5, type: !5, isLocal: false, isDefinition: true, scopeLine: 5, isOptimized: false, unit: !1, variables: !3)
!11 = distinct !DILocation(line: 6, scope: !10)
!12 = !DILocation(line: 2, scope: !4, inlinedAt: !11)
!13 = !DILocation(line: 3, scope: !4, inlinedAt: !11)