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ConstantHoisting: We can't insert instructions directly in front of a PHI node. 

Insert before the terminating instruction of the dominating block instead.

llvm-svn: 200218
This commit is contained in:
Benjamin Kramer 2014-01-27 13:11:43 +00:00
parent 7fe86589f1
commit 9e709bce86
3 changed files with 70 additions and 3 deletions
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21
llvm/lib/Transforms/Scalar/ConstantHoisting.cpp
View File

@ -311,6 +311,20 @@ FindConstantInsertionPoint(Function &F, const ConstantInfo &CI) const {
return (*BBs.begin())->getFirstInsertionPt();
}
/// \brief Find the instruction we should insert the constant materialization
/// before.
static Instruction *getMatInsertPt(Instruction *I, const DominatorTree *DT) {
if (!isa<PHINode>(I) && !isa<LandingPadInst>(I)) // Simple case.
return I;
// We can't insert directly before a phi node or landing pad. Insert before
// the terminator of the dominating block.
assert(&I->getParent()->getParent()->getEntryBlock() != I->getParent() &&
"PHI or landing pad in entry block!");
BasicBlock *IDom = DT->getNode(I->getParent())->getIDom()->getBlock();
return IDom->getTerminator();
}
/// \brief Emit materialization code for all rebased constants and update their
/// users.
void ConstantHoisting::EmitBaseConstants(Function &F, User *U,
@ -320,7 +334,7 @@ void ConstantHoisting::EmitBaseConstants(Function &F, User *U,
Instruction *Mat = Base;
if (!Offset->isNullValue()) {
Mat = BinaryOperator::Create(Instruction::Add, Base, Offset,
"const_mat", I);
"const_mat", getMatInsertPt(I, DT));
// Use the same debug location as the instruction we are about to update.
Mat->setDebugLoc(I->getDebugLoc());
@ -346,9 +360,10 @@ void ConstantHoisting::EmitBaseConstants(Function &F, User *U,
continue;
Instruction *Mat = Base;
Instruction *InsertBefore = getMatInsertPt(I, DT);
if (!Offset->isNullValue()) {
Mat = BinaryOperator::Create(Instruction::Add, Base, Offset,
"const_mat", I);
"const_mat", InsertBefore);
// Use the same debug location as the instruction we are about to
// update.
@ -360,7 +375,7 @@ void ConstantHoisting::EmitBaseConstants(Function &F, User *U,
}
Instruction *ICE = CE->getAsInstruction();
ICE->replaceUsesOfWith(OriginalConstant, Mat);
ICE->insertBefore(I);
ICE->insertBefore(InsertBefore);
// Use the same debug location as the instruction we are about to update.
ICE->setDebugLoc(I->getDebugLoc());

4
llvm/test/Transforms/ConstantHoisting/X86/lit.local.cfg Normal file
View File

@ -0,0 +1,4 @@
targets = set(config.root.targets_to_build.split())
if not 'X86' in targets:
config.unsupported = True

48
llvm/test/Transforms/ConstantHoisting/X86/phi.ll Normal file
View File

@ -0,0 +1,48 @@
; RUN: opt -S -consthoist < %s | FileCheck %s
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.9.0"
; PR18626
define i8* @test1(i1 %cmp, i64* %tmp) {
entry:
call void @foo(i8* inttoptr (i64 68719476735 to i8*))
br i1 %cmp, label %if.end, label %return
if.end: ; preds = %bb1
call void @foo(i8* inttoptr (i64 68719476736 to i8*))
br label %return
return:
%retval.0 = phi i8* [ null, %entry ], [ inttoptr (i64 68719476736 to i8*), %if.end ]
store i64 1172321806, i64* %tmp
ret i8* %retval.0
; CHECK-LABEL: @test1
; CHECK: entry:
; CHECK: %const_mat = add i64 %const, 1
; CHECK-NEXT: %1 = inttoptr i64 %const_mat to i8*
; CHECK-NEXT: br i1 %cmp
; CHECK: %retval.0 = phi i8* [ null, %entry ], [ %1, %if.end ]
}
define void @test2(i1 %cmp, i64** %tmp) {
entry:
call void @foo(i8* inttoptr (i64 68719476736 to i8*))
br i1 %cmp, label %if.end, label %return
if.end: ; preds = %bb1
call void @foo(i8* inttoptr (i64 68719476736 to i8*))
br label %return
return:
store i64* inttoptr (i64 68719476735 to i64*), i64** %tmp
ret void
; CHECK-LABEL: @test2
; CHECK: return:
; CHECK-NEXT: %const_mat = add i64 %const, -1
; CHECK-NEXT: inttoptr i64 %const_mat to i64*
}
declare void @foo(i8*)