[llvm] r281439 - Create a getelementptr instead of sub expr for ValueOffsetPair if the
Wei Mi via llvm-commits
llvm-commits at lists.llvm.org
Tue Sep 13 21:39:51 PDT 2016
Author: wmi
Date: Tue Sep 13 23:39:50 2016
New Revision: 281439
URL: http://llvm.org/viewvc/llvm-project?rev=281439&view=rev
Log:
Create a getelementptr instead of sub expr for ValueOffsetPair if the
value is a pointer.
This patch is to fix PR30213. When expanding an expr based on ValueOffsetPair,
if the value is of pointer type, we can only create a getelementptr instead
of sub expr.
Differential Revision: https://reviews.llvm.org/D24088
Added:
llvm/trunk/test/Analysis/ScalarEvolution/scev-expander-reuse-gep.ll
Modified:
llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp
Modified: llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp?rev=281439&r1=281438&r2=281439&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolutionExpander.cpp Tue Sep 13 23:39:50 2016
@@ -1703,9 +1703,28 @@ Value *SCEVExpander::expand(const SCEV *
if (!V)
V = visit(S);
- else if (VO.second)
- V = Builder.CreateSub(V, VO.second);
-
+ else if (VO.second) {
+ if (PointerType *Vty = dyn_cast<PointerType>(V->getType())) {
+ Type *Ety = Vty->getPointerElementType();
+ int64_t Offset = VO.second->getSExtValue();
+ int64_t ESize = SE.getTypeSizeInBits(Ety);
+ if ((Offset * 8) % ESize == 0) {
+ ConstantInt *Idx =
+ ConstantInt::getSigned(VO.second->getType(), -(Offset * 8) / ESize);
+ V = Builder.CreateGEP(Ety, V, Idx, "scevgep");
+ } else {
+ ConstantInt *Idx =
+ ConstantInt::getSigned(VO.second->getType(), -Offset);
+ unsigned AS = Vty->getAddressSpace();
+ V = Builder.CreateBitCast(V, Type::getInt8PtrTy(SE.getContext(), AS));
+ V = Builder.CreateGEP(Type::getInt8Ty(SE.getContext()), V, Idx,
+ "uglygep");
+ V = Builder.CreateBitCast(V, Vty);
+ }
+ } else {
+ V = Builder.CreateSub(V, VO.second);
+ }
+ }
// Remember the expanded value for this SCEV at this location.
//
// This is independent of PostIncLoops. The mapped value simply materializes
Added: llvm/trunk/test/Analysis/ScalarEvolution/scev-expander-reuse-gep.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/scev-expander-reuse-gep.ll?rev=281439&view=auto
==============================================================================
--- llvm/trunk/test/Analysis/ScalarEvolution/scev-expander-reuse-gep.ll (added)
+++ llvm/trunk/test/Analysis/ScalarEvolution/scev-expander-reuse-gep.ll Tue Sep 13 23:39:50 2016
@@ -0,0 +1,36 @@
+; PR30213. Check scev expand will generate correct code if the value
+; in ValueOffsetPair is of pointer type.
+; RUN: opt -mtriple=i386-apple-macosx10.12.0 < %s -loop-reduce -S | FileCheck %s
+
+; CHECK: %ptr4.ptr1 = select i1 %cmp.i, i8* %ptr4, i8* %ptr1
+; CHECK-NEXT: %scevgep = getelementptr i8, i8* %ptr4.ptr1, i32 1
+; CHECK-NEXT: br label %while.cond.i
+
+target datalayout = "e-m:o-p:32:32-f64:32:64-f80:128-n8:16:32-S128"
+target triple = "i386-apple-macosx10.12.0"
+
+; Function Attrs: nounwind optsize ssp
+define void @Foo() {
+entry:
+ switch i2 undef, label %sw.epilog102 [
+ i2 -2, label %sw.bb28
+ ]
+
+sw.bb28: ; preds = %entry
+ %0 = load i8*, i8** undef, align 2
+ %ptr1 = getelementptr inbounds i8, i8* undef, i32 -1
+ %ptr4 = getelementptr inbounds i8, i8* %0, i32 -1
+ %cmp.i = icmp ult i8* undef, %0
+ %ptr4.ptr1 = select i1 %cmp.i, i8* %ptr4, i8* %ptr1
+ br label %while.cond.i
+
+while.cond.i: ; preds = %while.cond.i, %sw.bb28
+ %currPtr.1.i = phi i8* [ %incdec.ptr.i, %while.cond.i ], [ %ptr4.ptr1, %sw.bb28 ]
+ %incdec.ptr.i = getelementptr inbounds i8, i8* %currPtr.1.i, i32 1
+ %1 = load i8, i8* %incdec.ptr.i, align 1
+ br label %while.cond.i
+
+sw.epilog102: ; preds = %entry
+ unreachable
+}
+
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