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[TTI] Fix getGEPCost() for geps with a single operand. 

Previously this would sporadically crash as TargetType
was never initialized. We special-case the single-operand
case returning earlier and trying to mimic the behaviour of
isLegalAddressingMode as closely as possible.

Differential Revision:  https://reviews.llvm.org/D37277

llvm-svn: 312357
This commit is contained in:
Davide Italiano 2017-09-01 19:54:08 +00:00
parent 07490f8415
commit c36039f462
2 changed files with 34 additions and 0 deletions
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6
llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
View File

@ -675,6 +675,12 @@ public:
auto GTI = gep_type_begin(PointeeType, Operands); auto GTI = gep_type_begin(PointeeType, Operands);
Type *TargetType = nullptr; Type *TargetType = nullptr;
// Handle the case where the GEP instruction has a single operand,
// the basis, therefore TargetType is a nullptr.
if (Operands.empty())
return !BaseGV ? TTI::TCC_Free : TTI::TCC_Basic;
for (auto I = Operands.begin(); I != Operands.end(); ++I, ++GTI) { for (auto I = Operands.begin(); I != Operands.end(); ++I, ++GTI) {
TargetType = GTI.getIndexedType(); TargetType = GTI.getIndexedType();
// We assume that the cost of Scalar GEP with constant index and the // We assume that the cost of Scalar GEP with constant index and the

28
llvm/test/Transforms/SimplifyCFG/gepcost.ll Normal file
View File

@ -0,0 +1,28 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -S -simplifycfg | FileCheck %s
target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "thumbv7m-none--eabi"
@glob = external unnamed_addr constant [16 x i8]
define void @f() {
; CHECK-LABEL: @f(
; CHECK-NEXT: entr:
; CHECK-NEXT: br i1 undef, label [[NEXT:%.*]], label [[EXIT:%.*]]
; CHECK: next:
; CHECK-NEXT: [[PAT:%.*]] = getelementptr [16 x i8], [16 x i8]* @glob
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: ret void
;
entr:
br i1 undef, label %next, label %exit
next:
%pat = getelementptr [16 x i8], [16 x i8]* @glob
br label %exit
exit:
ret void
}