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

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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 2 of 8 for D26256.  Folding of a binary operation.

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

llvm-svn: 289679
This commit is contained in:
Robert Lougher 2016-12-14 17:49:19 +00:00
parent a322040bdf
commit bf534d3173
3 changed files with 91 additions and 1 deletions
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4
lib/Transforms/InstCombine/InstCombineInternal.h
View File

@ -553,6 +553,10 @@ private:
Instruction *FoldPHIArgLoadIntoPHI(PHINode &PN);
Instruction *FoldPHIArgZextsIntoPHI(PHINode &PN);
/// Helper function for FoldPHIArgXIntoPHI() to get debug location for the
/// folded operation.
DebugLoc PHIArgMergedDebugLoc(PHINode &PN);
Instruction *foldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
ICmpInst::Predicate Cond, Instruction &I);
Instruction *foldAllocaCmp(ICmpInst &ICI, const AllocaInst *Alloca,

18
lib/Transforms/InstCombine/InstCombinePHI.cpp
View File

@ -18,11 +18,27 @@
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/IR/DebugInfo.h"
using namespace llvm;
using namespace llvm::PatternMatch;
#define DEBUG_TYPE "instcombine"
/// The PHI arguments will be folded into a single operation with a PHI node
/// as input. The debug location of the single operation will be the merged
/// locations of the original PHI node arguments.
DebugLoc InstCombiner::PHIArgMergedDebugLoc(PHINode &PN) {
auto *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
DILocation *Loc = FirstInst->getDebugLoc();
for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
auto *I = cast<Instruction>(PN.getIncomingValue(i));
Loc = DILocation::getMergedLocation(Loc, I->getDebugLoc());
}
return Loc;
}
/// If we have something like phi [add (a,b), add(a,c)] and if a/b/c and the
/// adds all have a single use, turn this into a phi and a single binop.
Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
@ -114,7 +130,7 @@ Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i)
NewBinOp->andIRFlags(PN.getIncomingValue(i));
NewBinOp->setDebugLoc(FirstInst->getDebugLoc());
NewBinOp->setDebugLoc(PHIArgMergedDebugLoc(PN));
return NewBinOp;
}

70
test/DebugInfo/Generic/instcombine-phi.ll Normal file
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@ -0,0 +1,70 @@
; RUN: opt -instcombine -S < %s | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
; 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. Check that when it does this the combined operation does not
; have a debug location set.
; Test folding of a binary operation. Generated from source:
; extern int foo(void);
; extern int bar(void);
;
; int binop(int a, int b) {
; if(a)
; b -= foo();
; else
; b -= bar();
; return b;
; }
; CHECK: define i32 @binop
; CHECK-LABEL: if.end:
; CHECK: %[[PHI:.*]] = phi i32 [ %call, %if.then ], [ %call1, %if.else ]
; CHECK: sub nsw i32 %b, %[[PHI]]
; CHECK-NOT: !dbg
; CHECK: ret i32
define i32 @binop(i32 %a, i32 %b) !dbg !6 {
entry:
%tobool = icmp ne i32 %a, 0, !dbg !8
br i1 %tobool, label %if.then, label %if.else, !dbg !8
if.then: ; preds = %entry
%call = call i32 @foo(), !dbg !9
%sub = sub nsw i32 %b, %call, !dbg !10
br label %if.end, !dbg !11
if.else: ; preds = %entry
%call1 = call i32 @bar(), !dbg !12
%sub2 = sub nsw i32 %b, %call1, !dbg !13
br label %if.end
if.end: ; preds = %if.else, %if.then
%b.addr.0 = phi i32 [ %sub, %if.then ], [ %sub2, %if.else ]
ret i32 %b.addr.0, !dbg !14
}
declare i32 @foo()
declare i32 @bar()
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "", isOptimized: false, runtimeVersion: 0, emissionKind: LineTablesOnly, enums: !2)
!1 = !DIFile(filename: "test.c", directory: "")
!2 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!6 = distinct !DISubprogram(name: "binop", scope: !1, file: !1, line: 8, type: !7, isLocal: false, isDefinition: true, scopeLine: 8, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
!7 = !DISubroutineType(types: !2)
!8 = !DILocation(line: 9, column: 6, scope: !6)
!9 = !DILocation(line: 10, column: 10, scope: !6)
!10 = !DILocation(line: 10, column: 7, scope: !6)
!11 = !DILocation(line: 10, column: 5, scope: !6)
!12 = !DILocation(line: 12, column: 10, scope: !6)
!13 = !DILocation(line: 12, column: 7, scope: !6)
!14 = !DILocation(line: 13, column: 3, scope: !6)