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[ConstantFold] Don't fold ppc_fp128 <-> int bitcasts

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PPC_FP128 is really the sum of two consecutive doubles, where the first double
is always stored first in memory, regardless of the target endianness. The
memory layout of i128, however, depends on the target endianness, and so we
can't fold this without target endianness information. As a result, we must not
do this folding in lib/IR/ConstantFold.cpp (it could be done instead in
Analysis/ConstantFolding.cpp, but that's not done now).

Fixes PR23026.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233481 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hal Finkel 2015-03-28 16:44:57 +00:00
parent 5ce6ef629e
commit 8360002904
2 changed files with 49 additions and 2 deletions
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15
lib/IR/ConstantFold.cpp
View File

@ -169,7 +169,8 @@ static Constant *FoldBitCast(Constant *V, Type *DestTy) {
// be the same. Consequently, we just fold to V.
return V;
if (DestTy->isFloatingPointTy())
// See note below regarding the PPC_FP128 restriction.
if (DestTy->isFloatingPointTy() && !DestTy->isPPC_FP128Ty())
return ConstantFP::get(DestTy->getContext(),
APFloat(DestTy->getFltSemantics(),
CI->getValue()));
@ -179,9 +180,19 @@ static Constant *FoldBitCast(Constant *V, Type *DestTy) {
}
// Handle ConstantFP input: FP -> Integral.
if (ConstantFP *FP = dyn_cast<ConstantFP>(V))
if (ConstantFP *FP = dyn_cast<ConstantFP>(V)) {
// PPC_FP128 is really the sum of two consecutive doubles, where the first
// double is always stored first in memory, regardless of the target
// endianness. The memory layout of i128, however, depends on the target
// endianness, and so we can't fold this without target endianness
// information. This should instead be handled by
// Analysis/ConstantFolding.cpp
if (FP->getType()->isPPC_FP128Ty())
return nullptr;
return ConstantInt::get(FP->getContext(),
FP->getValueAPF().bitcastToAPInt());
}
return nullptr;
}

36
test/Transforms/SROA/ppcf128-no-fold.ll Normal file
View File

@ -0,0 +1,36 @@
; RUN: opt < %s -sroa -S | FileCheck %s
target datalayout = "E-m:e-i64:64-n32:64"
target triple = "powerpc64-unknown-linux-gnu"
%struct.ld2 = type { [2 x ppc_fp128] }
declare void @bar(i8*, [2 x i128])
define void @foo(i8* %v) #0 {
entry:
%v.addr = alloca i8*, align 8
%z = alloca %struct.ld2, align 16
store i8* %v, i8** %v.addr, align 8
%dat = getelementptr inbounds %struct.ld2, %struct.ld2* %z, i32 0, i32 0
%arrayidx = getelementptr inbounds [2 x ppc_fp128], [2 x ppc_fp128]* %dat, i32 0, i64 0
store ppc_fp128 0xM403B0000000000000000000000000000, ppc_fp128* %arrayidx, align 16
%dat1 = getelementptr inbounds %struct.ld2, %struct.ld2* %z, i32 0, i32 0
%arrayidx2 = getelementptr inbounds [2 x ppc_fp128], [2 x ppc_fp128]* %dat1, i32 0, i64 1
store ppc_fp128 0xM4093B400000000000000000000000000, ppc_fp128* %arrayidx2, align 16
%0 = load i8*, i8** %v.addr, align 8
%coerce.dive = getelementptr %struct.ld2, %struct.ld2* %z, i32 0, i32 0
%1 = bitcast [2 x ppc_fp128]* %coerce.dive to [2 x i128]*
%2 = load [2 x i128], [2 x i128]* %1, align 1
call void @bar(i8* %0, [2 x i128] %2)
ret void
}
; CHECK-LABEL: @foo
; CHECK-NOT: i128 4628293042053316608
; CHECK-NOT: i128 4653260752096854016
; CHECK-DAG: i128 bitcast (ppc_fp128 0xM403B0000000000000000000000000000 to i128)
; CHECK-DAG: i128 bitcast (ppc_fp128 0xM4093B400000000000000000000000000 to i128)
; CHECK: call void @bar(i8* %v, [2 x i128]
; CHECK: ret void
attributes #0 = { nounwind }