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[InstCombine] When folding casts through a phi node merge the debug locations 

If all the operands to a phi node are a cast, instcombine will try to pull
them through the phi node, combining them into a single cast. When it does
this, the debug location of the new cast should be the merged debug locations
of the phi node arguments.

Patch 6 of 8 for D26256.  Folding of a cast operation.

Differential Revision: https://reviews.llvm.org/D26256

llvm-svn: 289693
This commit is contained in:
Robert Lougher 2016-12-14 19:24:01 +00:00
parent 64aec507e8
commit f02d9b8325
2 changed files with 48 additions and 1 deletions
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2
llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
View File

@ -565,7 +565,7 @@ Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
if (CastInst *FirstCI = dyn_cast<CastInst>(FirstInst)) {
CastInst *NewCI = CastInst::Create(FirstCI->getOpcode(), PhiVal,
PN.getType());
NewCI->setDebugLoc(FirstInst->getDebugLoc());
NewCI->setDebugLoc(PHIArgMergedDebugLoc(PN));
return NewCI;
}

47
llvm/test/DebugInfo/Generic/instcombine-phi.ll
View File

@ -173,6 +173,47 @@ if.end: ; preds = %if.else, %if.then
ret i32 %r.0, !dbg !38
}
; Test folding of a cast. Generated from source:
; extern int foo(void);
; extern int bar(void);
;
; long long cast(int a) {
; long long r;
; if(a)
; r = foo();
; else
; r = bar();
; return r;
; }
; CHECK: define i64 @cast
; CHECK-LABEL: if.end:
; CHECK: %[[PHI:.*]] = phi i32 [ %call, %if.then ], [ %call1, %if.else ]
; CHECK: sext i32 %[[PHI]] to i64
; CHECK-NOT: !dbg
; CHECK: ret i64
define i64 @cast(i32 %a) !dbg !39 {
entry:
%tobool = icmp ne i32 %a, 0, !dbg !40
br i1 %tobool, label %if.then, label %if.else, !dbg !40
if.then: ; preds = %entry
%call = call i32 @foo(), !dbg !41
%conv = sext i32 %call to i64, !dbg !41
br label %if.end, !dbg !42
if.else: ; preds = %entry
%call1 = call i32 @bar(), !dbg !43
%conv2 = sext i32 %call1 to i64, !dbg !43
br label %if.end
if.end: ; preds = %if.else, %if.then
%r.0 = phi i64 [ %conv, %if.then ], [ %conv2, %if.else ]
ret i64 %r.0, !dbg !44
}
declare i32 @foo()
declare i32 @bar()
declare i64 @foo2()
@ -221,3 +262,9 @@ declare i32* @bar3()
!36 = !DILocation(line: 39, column: 10, scope: !31)
!37 = !DILocation(line: 39, column: 9, scope: !31)
!38 = !DILocation(line: 40, column: 3, scope: !31)
!39 = distinct !DISubprogram(name: "cast", scope: !1, file: !1, line: 43, type: !7, isLocal: false, isDefinition: true, scopeLine: 43, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
!40 = !DILocation(line: 45, column: 6, scope: !39)
!41 = !DILocation(line: 46, column: 9, scope: !39)
!42 = !DILocation(line: 46, column: 5, scope: !39)
!43 = !DILocation(line: 48, column: 9, scope: !39)
!44 = !DILocation(line: 49, column: 3, scope: !39)