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[InstCombine] Folding of a binop with RHS const should merge the debug locations 

If all the operands to a phi node are a binop with a RHS constant, 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 new op should be the
merged debug locations of the phi node arguments.

Patch 7 of 8 for D26256.  Folding of a binop with RHS constant.

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

llvm-svn: 289699
This commit is contained in:
Robert Lougher 2016-12-14 20:07:49 +00:00
parent 418ed82eae
commit c9f7354776
2 changed files with 50 additions and 1 deletions
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2
llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
View File

@ -576,7 +576,7 @@ Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i)
BinOp->andIRFlags(PN.getIncomingValue(i));
BinOp->setDebugLoc(FirstInst->getDebugLoc());
BinOp->setDebugLoc(PHIArgMergedDebugLoc(PN));
return BinOp;
}

49
llvm/test/DebugInfo/Generic/instcombine-phi.ll
View File

@ -214,6 +214,47 @@ if.end: ; preds = %if.else, %if.then
ret i64 %r.0, !dbg !44
}
; Test folding of a binary op with a RHS constant. Generated from source:
; extern int foo(void);
; extern int bar(void);
;
; int binop_const(int a) {
; int r;
; if(a)
; r = foo() - 5;
; else
; r = bar() - 5;
; return r;
; }
; CHECK: define i32 @binop_const
; CHECK-LABEL: if.end:
; CHECK: %[[PHI:.*]] = phi i32 [ %call, %if.then ], [ %call1, %if.else ]
; CHECK: add nsw i32 %[[PHI]], -5
; CHECK-NOT: !dbg
; CHECK: ret i32
define i32 @binop_const(i32 %a) !dbg !45 {
entry:
%tobool = icmp ne i32 %a, 0, !dbg !46
br i1 %tobool, label %if.then, label %if.else, !dbg !46
if.then: ; preds = %entry
%call = call i32 @foo(), !dbg !47
%sub = sub nsw i32 %call, 5, !dbg !48
br label %if.end, !dbg !49
if.else: ; preds = %entry
%call1 = call i32 @bar(), !dbg !50
%sub2 = sub nsw i32 %call1, 5, !dbg !51
br label %if.end
if.end: ; preds = %if.else, %if.then
%r.0 = phi i32 [ %sub, %if.then ], [ %sub2, %if.else ]
ret i32 %r.0, !dbg !52
}
declare i32 @foo()
declare i32 @bar()
declare i64 @foo2()
@ -268,3 +309,11 @@ declare i32* @bar3()
!42 = !DILocation(line: 46, column: 5, scope: !39)
!43 = !DILocation(line: 48, column: 9, scope: !39)
!44 = !DILocation(line: 49, column: 3, scope: !39)
!45 = distinct !DISubprogram(name: "binop_const", scope: !1, file: !1, line: 52, type: !7, isLocal: false, isDefinition: true, scopeLine: 52, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
!46 = !DILocation(line: 54, column: 6, scope: !45)
!47 = !DILocation(line: 55, column: 9, scope: !45)
!48 = !DILocation(line: 55, column: 15, scope: !45)
!49 = !DILocation(line: 55, column: 5, scope: !45)
!50 = !DILocation(line: 57, column: 9, scope: !45)
!51 = !DILocation(line: 57, column: 15, scope: !45)
!52 = !DILocation(line: 58, column: 3, scope: !45)