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[DAGCombiner] Fix & simplify constant folding of sext/zext.

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Summary: This patch fixes the cases of sext/zext constant folding in DAG combiner where constans do not fit 64 bits. The fix simply removes un$

Test Plan: New regression test included.

Reviewers: RKSimon

Reviewed By: RKSimon

Subscribers: RKSimon, llvm-commits

Differential Revision: http://reviews.llvm.org/D10607

llvm-svn: 240991
This commit is contained in:
Pawel Bylica 2015-06-29 20:28:47 +00:00
parent 89234b3b07
commit 7882eec9af
2 changed files with 103 additions and 13 deletions
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24
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -5579,12 +5579,12 @@ SDValue DAGCombiner::visitSETCC(SDNode *N) {
SDLoc(N)); SDLoc(N));
} }
// tryToFoldExtendOfConstant - Try to fold a sext/zext/aext /// Try to fold a sext/zext/aext dag node into a ConstantSDNode or
// dag node into a ConstantSDNode or a build_vector of constants. /// a build_vector of constants.
// This function is called by the DAGCombiner when visiting sext/zext/aext /// This function is called by the DAGCombiner when visiting sext/zext/aext
// dag nodes (see for example method DAGCombiner::visitSIGN_EXTEND). /// dag nodes (see for example method DAGCombiner::visitSIGN_EXTEND).
// Vector extends are not folded if operations are legal; this is to /// Vector extends are not folded if operations are legal; this is to
// avoid introducing illegal build_vector dag nodes. /// avoid introducing illegal build_vector dag nodes.
static SDNode *tryToFoldExtendOfConstant(SDNode *N, const TargetLowering &TLI, static SDNode *tryToFoldExtendOfConstant(SDNode *N, const TargetLowering &TLI,
SelectionDAG &DAG, bool LegalTypes, SelectionDAG &DAG, bool LegalTypes,
bool LegalOperations) { bool LegalOperations) {
@ -5614,7 +5614,6 @@ static SDNode *tryToFoldExtendOfConstant(SDNode *N, const TargetLowering &TLI,
// We can fold this node into a build_vector. // We can fold this node into a build_vector.
unsigned VTBits = SVT.getSizeInBits(); unsigned VTBits = SVT.getSizeInBits();
unsigned EVTBits = N0->getValueType(0).getScalarType().getSizeInBits(); unsigned EVTBits = N0->getValueType(0).getScalarType().getSizeInBits();
unsigned ShAmt = VTBits - EVTBits;
SmallVector<SDValue, 8> Elts; SmallVector<SDValue, 8> Elts;
unsigned NumElts = VT.getVectorNumElements(); unsigned NumElts = VT.getVectorNumElements();
SDLoc DL(N); SDLoc DL(N);
@ -5627,14 +5626,13 @@ static SDNode *tryToFoldExtendOfConstant(SDNode *N, const TargetLowering &TLI,
} }
SDLoc DL(Op); SDLoc DL(Op);
ConstantSDNode *CurrentND = cast<ConstantSDNode>(Op); // Get the constant value and if needed trunc it to the size of the type.
const APInt &C = APInt(VTBits, CurrentND->getAPIntValue().getZExtValue()); // Nodes like build_vector might have constants wider than the scalar type.
APInt C = cast<ConstantSDNode>(Op)->getAPIntValue().zextOrTrunc(EVTBits);
if (Opcode == ISD::SIGN_EXTEND || Opcode == ISD::SIGN_EXTEND_VECTOR_INREG) if (Opcode == ISD::SIGN_EXTEND || Opcode == ISD::SIGN_EXTEND_VECTOR_INREG)
Elts.push_back(DAG.getConstant(C.shl(ShAmt).ashr(ShAmt).getZExtValue(), Elts.push_back(DAG.getConstant(C.sext(VTBits), DL, SVT));
DL, SVT));
else else
Elts.push_back(DAG.getConstant(C.shl(ShAmt).lshr(ShAmt).getZExtValue(), Elts.push_back(DAG.getConstant(C.zext(VTBits), DL, SVT));
DL, SVT));
} }
return DAG.getNode(ISD::BUILD_VECTOR, DL, VT, Elts).getNode(); return DAG.getNode(ISD::BUILD_VECTOR, DL, VT, Elts).getNode();

92
test/CodeGen/X86/fold-vector-sext-crash2.ll Normal file
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@ -0,0 +1,92 @@
; RUN: llc < %s -march=x86 | FileCheck %s -check-prefix=X32
; RUN: llc < %s -march=x86-64 | FileCheck %s -check-prefix=X64
; DAGCombiner crashes during sext folding
define <2 x i256> @test_sext1() {
%Se = sext <2 x i8> <i8 -100, i8 -99> to <2 x i256>
%Shuff = shufflevector <2 x i256> zeroinitializer, <2 x i256> %Se, <2 x i32> <i32 1, i32 3>
ret <2 x i256> %Shuff
; X64-LABEL: test_sext1
; X64: movq $-1
; X64-NEXT: movq $-1
; X64-NEXT: movq $-1
; X64-NEXT: movq $-99
; X32-LABEL: test_sext1
; X32: movl $-1
; X32-NEXT: movl $-1
; X32-NEXT: movl $-1
; X32-NEXT: movl $-1
; X32-NEXT: movl $-1
; X32-NEXT: movl $-1
; X32-NEXT: movl $-1
; X32-NEXT: movl $-99
}
define <2 x i256> @test_sext2() {
%Se = sext <2 x i128> <i128 -2000, i128 -1999> to <2 x i256>
%Shuff = shufflevector <2 x i256> zeroinitializer, <2 x i256> %Se, <2 x i32> <i32 1, i32 3>
ret <2 x i256> %Shuff
; X64-LABEL: test_sext2
; X64: movq $-1
; X64-NEXT: movq $-1
; X64-NEXT: movq $-1
; X64-NEXT: movq $-1999
; X32-LABEL: test_sext2
; X32: movl $-1
; X32-NEXT: movl $-1
; X32-NEXT: movl $-1
; X32-NEXT: movl $-1
; X32-NEXT: movl $-1
; X32-NEXT: movl $-1
; X32-NEXT: movl $-1
; X32-NEXT: movl $-1999
}
define <2 x i256> @test_zext1() {
%Se = zext <2 x i8> <i8 -1, i8 -2> to <2 x i256>
%Shuff = shufflevector <2 x i256> zeroinitializer, <2 x i256> %Se, <2 x i32> <i32 1, i32 3>
ret <2 x i256> %Shuff
; X64-LABEL: test_zext1
; X64: movq $0
; X64-NEXT: movq $0
; X64-NEXT: movq $0
; X64-NEXT: movq $254
; X32-LABEL: test_zext1
; X32: movl $0
; X32-NEXT: movl $0
; X32-NEXT: movl $0
; X32-NEXT: movl $0
; X32-NEXT: movl $0
; X32-NEXT: movl $0
; X32-NEXT: movl $0
; X32-NEXT: movl $254
}
define <2 x i256> @test_zext2() {
%Se = zext <2 x i128> <i128 -1, i128 -2> to <2 x i256>
%Shuff = shufflevector <2 x i256> zeroinitializer, <2 x i256> %Se, <2 x i32> <i32 1, i32 3>
ret <2 x i256> %Shuff
; X64-LABEL: test_zext2
; X64: movq $0
; X64-NEXT: movq $0
; X64-NEXT: movq $-1
; X64-NEXT: movq $-2
; X32-LABEL: test_zext2
; X32: movl $0
; X32-NEXT: movl $0
; X32-NEXT: movl $0
; X32-NEXT: movl $0
; X32-NEXT: movl $-1
; X32-NEXT: movl $-1
; X32-NEXT: movl $-1
; X32-NEXT: movl $-2
}