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SCEVExpander: Fold constant PHIs harder. The logic below only understands proper IVs.

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PR20093.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211433 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2014-06-21 11:47:18 +00:00
parent 7921239c41
commit b7f1fb47e6
2 changed files with 53 additions and 1 deletions
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3
lib/Analysis/ScalarEvolutionExpander.cpp
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@ -16,6 +16,7 @@
#include "llvm/Analysis/ScalarEvolutionExpander.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/IR/DataLayout.h"
@ -1706,7 +1707,7 @@ unsigned SCEVExpander::replaceCongruentIVs(Loop *L, const DominatorTree *DT,
// Fold constant phis. They may be congruent to other constant phis and
// would confuse the logic below that expects proper IVs.
if (Value *V = Phi->hasConstantValue()) {
if (Value *V = SimplifyInstruction(Phi, SE.DL, SE.TLI, SE.DT)) {
Phi->replaceAllUsesWith(V);
DeadInsts.push_back(Phi);
++NumElim;

51
test/Transforms/IndVarSimplify/2014-06-21-congruent-constant.ll Normal file
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@ -0,0 +1,51 @@
; RUN: opt -S -loop-unswitch -instcombine -indvars < %s | FileCheck %s
@c = external global i32**, align 8
define void @test1() {
entry:
br i1 undef, label %for.end12, label %for.cond.preheader
for.cond.preheader: ; preds = %entry
%0 = load i32*** @c, align 8
%1 = load i32** %0, align 8
%2 = load i32* %1, align 4
br label %for.body
for.body: ; preds = %for.cond.backedge, %for.body9.us, %for.cond.preheader
%3 = phi i32* [ %1, %for.cond.preheader ], [ %3, %for.cond.backedge ], [ %6, %for.body9.us ]
%4 = phi i32 [ %2, %for.cond.preheader ], [ undef, %for.cond.backedge ], [ %7, %for.body9.us ]
%i.024 = phi i32 [ 0, %for.cond.preheader ], [ %inc, %for.cond.backedge ], [ 0, %for.body9.us ]
%tobool1 = icmp eq i32 %4, 0
br i1 %tobool1, label %if.end, label %for.cond.backedge
if.end: ; preds = %for.body
%5 = load i32* %3, align 4
%tobool4 = icmp eq i32 %5, 0
br i1 %tobool4, label %for.cond3, label %for.body9.preheader
for.body9.preheader: ; preds = %if.end
%tobool8 = icmp eq i32 %i.024, 1
br i1 %tobool8, label %for.body9.us, label %for.body9
for.body9.us: ; preds = %for.body9.preheader
%6 = load i32** undef, align 8
%7 = load i32* %6, align 4
br label %for.body
for.cond3: ; preds = %for.cond3, %if.end
br label %for.cond3
for.body9: ; preds = %for.body9, %for.body9.preheader
br label %for.body9
for.cond.backedge: ; preds = %for.body
%inc = add nsw i32 %i.024, 1
br i1 false, label %for.body, label %for.end12
for.end12: ; preds = %for.cond.backedge, %entry
ret void
; CHECK-LABEL: @test1
; CHECK-NOT: phi
}