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[InstCombine] Merge debug locations when folding through a phi node 

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

Patch 3 of 8 for D26256.  Folding of a compare operation.

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

llvm-svn: 289681
This commit is contained in:
Robert Lougher 2016-12-14 18:14:57 +00:00
parent d9d9a54511
commit 4b0790d488
2 changed files with 52 additions and 1 deletions
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2
llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
View File

@ -117,7 +117,7 @@ Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst)) {
CmpInst *NewCI = CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
LHSVal, RHSVal);
NewCI->setDebugLoc(FirstInst->getDebugLoc());
NewCI->setDebugLoc(PHIArgMergedDebugLoc(PN));
return NewCI;
}

51
llvm/test/DebugInfo/Generic/instcombine-phi.ll
View File

@ -48,6 +48,49 @@ if.end: ; preds = %if.else, %if.then
ret i32 %b.addr.0, !dbg !14
}
; Test folding of a compare. Generated from source (with editing to
; common the zext):
; extern int foo(void);
; extern int bar(void);
;
; int cmp(int a, int b) {
; int r;
; if(a)
; r = foo() < b;
; else
; r = bar() < b;
; return r;
; }
; CHECK: define i32 @cmp
; CHECK-LABEL: if.end:
; CHECK: %[[PHI:.*]] = phi i32 [ %call, %if.then ], [ %call1, %if.else ]
; CHECK: icmp slt i32 %[[PHI]], %b
; CHECK-NOT: !dbg
; CHECK: ret i32
define i32 @cmp(i32 %a, i32 %b) !dbg !15 {
entry:
%tobool = icmp ne i32 %a, 0, !dbg !16
br i1 %tobool, label %if.then, label %if.else, !dbg !16
if.then: ; preds = %entry
%call = call i32 @foo(), !dbg !17
%cmp = icmp slt i32 %call, %b, !dbg !18
br label %if.end, !dbg !19
if.else: ; preds = %entry
%call1 = call i32 @bar(), !dbg !20
%cmp2 = icmp slt i32 %call1, %b, !dbg !21
br label %if.end
if.end: ; preds = %if.else, %if.then
%r.0 = phi i1 [ %cmp, %if.then ], [ %cmp2, %if.else ]
%conv = zext i1 %r.0 to i32
ret i32 %conv, !dbg !22
}
declare i32 @foo()
declare i32 @bar()
@ -68,3 +111,11 @@ declare i32 @bar()
!12 = !DILocation(line: 12, column: 10, scope: !6)
!13 = !DILocation(line: 12, column: 7, scope: !6)
!14 = !DILocation(line: 13, column: 3, scope: !6)
!15 = distinct !DISubprogram(name: "cmp", scope: !1, file: !1, line: 16, type: !7, isLocal: false, isDefinition: true, scopeLine: 16, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
!16 = !DILocation(line: 18, column: 6, scope: !15)
!17 = !DILocation(line: 19, column: 9, scope: !15)
!18 = !DILocation(line: 19, column: 15, scope: !15)
!19 = !DILocation(line: 19, column: 5, scope: !15)
!20 = !DILocation(line: 21, column: 9, scope: !15)
!21 = !DILocation(line: 21, column: 15, scope: !15)
!22 = !DILocation(line: 22, column: 3, scope: !15)