[llvm] r280927 - [SelectionDAG] Add BUILD_VECTOR support to computeKnownBits and SimplifyDemandedBits
Simon Pilgrim via llvm-commits
llvm-commits at lists.llvm.org
Thu Sep 8 05:57:52 PDT 2016
Author: rksimon
Date: Thu Sep 8 07:57:51 2016
New Revision: 280927
URL: http://llvm.org/viewvc/llvm-project?rev=280927&view=rev
Log:
[SelectionDAG] Add BUILD_VECTOR support to computeKnownBits and SimplifyDemandedBits
Add the ability to computeKnownBits and SimplifyDemandedBits to extract the known zero/one bits from BUILD_VECTOR, returning the known bits that are shared by every vector element.
This is an initial step towards determining the sign bits of a vector (PR29079).
Differential Revision: https://reviews.llvm.org/D24253
Modified:
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp
llvm/trunk/test/CodeGen/AMDGPU/load-constant-i16.ll
llvm/trunk/test/CodeGen/AMDGPU/load-global-i16.ll
llvm/trunk/test/CodeGen/X86/combine-and.ll
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp?rev=280927&r1=280926&r2=280927&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp Thu Sep 8 07:57:51 2016
@@ -2016,6 +2016,26 @@ void SelectionDAG::computeKnownBits(SDVa
KnownOne = cast<ConstantSDNode>(Op)->getAPIntValue();
KnownZero = ~KnownOne;
break;
+ case ISD::BUILD_VECTOR:
+ // Collect the known bits that are shared by every vector element.
+ KnownZero = KnownOne = APInt::getAllOnesValue(BitWidth);
+ for (SDValue SrcOp : Op->ops()) {
+ computeKnownBits(SrcOp, KnownZero2, KnownOne2, Depth + 1);
+
+ // BUILD_VECTOR can implicitly truncate sources, we must handle this.
+ if (SrcOp.getValueSizeInBits() != BitWidth) {
+ assert(SrcOp.getValueSizeInBits() > BitWidth &&
+ "Expected BUILD_VECTOR implicit truncation");
+ KnownOne2 = KnownOne2.trunc(BitWidth);
+ KnownZero2 = KnownZero2.trunc(BitWidth);
+ }
+
+ // Known bits are the values that are shared by every element.
+ // TODO: support per-element known bits.
+ KnownOne &= KnownOne2;
+ KnownZero &= KnownZero2;
+ }
+ break;
case ISD::AND:
// If either the LHS or the RHS are Zero, the result is zero.
computeKnownBits(Op.getOperand(1), KnownZero, KnownOne, Depth+1);
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp?rev=280927&r1=280926&r2=280927&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp Thu Sep 8 07:57:51 2016
@@ -468,6 +468,33 @@ bool TargetLowering::SimplifyDemandedBit
KnownOne = cast<ConstantSDNode>(Op)->getAPIntValue();
KnownZero = ~KnownOne;
return false; // Don't fall through, will infinitely loop.
+ case ISD::BUILD_VECTOR:
+ // Collect the known bits that are shared by every constant vector element.
+ KnownZero = KnownOne = APInt::getAllOnesValue(BitWidth);
+ for (SDValue SrcOp : Op->ops()) {
+ if (!isa<ConstantSDNode>(SrcOp)) {
+ // We can only handle all constant values - bail out with no known bits.
+ KnownZero = KnownOne = APInt(BitWidth, 0);
+ return false;
+ }
+ KnownOne2 = cast<ConstantSDNode>(SrcOp)->getAPIntValue();
+ KnownZero2 = ~KnownOne2;
+
+ // BUILD_VECTOR can implicitly truncate sources, we must handle this.
+ if (KnownOne2.getBitWidth() != BitWidth) {
+ assert(KnownOne2.getBitWidth() > BitWidth &&
+ KnownZero2.getBitWidth() > BitWidth &&
+ "Expected BUILD_VECTOR implicit truncation");
+ KnownOne2 = KnownOne2.trunc(BitWidth);
+ KnownZero2 = KnownZero2.trunc(BitWidth);
+ }
+
+ // Known bits are the values that are shared by every element.
+ // TODO: support per-element known bits.
+ KnownOne &= KnownOne2;
+ KnownZero &= KnownZero2;
+ }
+ return false; // Don't fall through, will infinitely loop.
case ISD::AND:
// If the RHS is a constant, check to see if the LHS would be zero without
// using the bits from the RHS. Below, we use knowledge about the RHS to
Modified: llvm/trunk/test/CodeGen/AMDGPU/load-constant-i16.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AMDGPU/load-constant-i16.ll?rev=280927&r1=280926&r2=280927&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AMDGPU/load-constant-i16.ll (original)
+++ llvm/trunk/test/CodeGen/AMDGPU/load-constant-i16.ll Thu Sep 8 07:57:51 2016
@@ -138,7 +138,7 @@ define void @constant_sextload_v1i16_to_
; v2i16 is naturally 4 byte aligned
; EG: VTX_READ_32 [[DST:T[0-9]\.[XYZW]]], [[DST]], 0, #1
; TODO: This should use DST, but for some there are redundant MOVs
-; EG: LSHR {{[* ]*}}T{{[0-9].[XYZW]}}, {{PV.[XYZW]}}, literal
+; EG: BFE_UINT {{[* ]*}}T{{[0-9].[XYZW]}}, {{PV.[XYZW]}}, literal
; EG: 16
define void @constant_zextload_v2i16_to_v2i32(<2 x i32> addrspace(1)* %out, <2 x i16> addrspace(2)* %in) #0 {
%load = load <2 x i16>, <2 x i16> addrspace(2)* %in
@@ -212,9 +212,10 @@ entry:
; v4i16 is naturally 8 byte aligned
; EG: VTX_READ_64 [[DST:T[0-9]\.XY]], {{T[0-9].[XYZW]}}, 0, #1
; TODO: These should use DST, but for some there are redundant MOVs
-; EG-DAG: LSHR {{[* ]*}}T{{[0-9].[XYZW]}}, {{PV.[XYZW]}}, literal
-; EG-DAG: LSHR {{[* ]*}}T{{[0-9].[XYZW]}}, {{T[0-9].[XYZW]}}, literal
+; EG-DAG: BFE_UINT {{[* ]*}}T{{[0-9].[XYZW]}}, {{PV.[XYZW]}}, literal
; EG-DAG: 16
+; EG-DAG: BFE_UINT {{[* ]*}}T{{[0-9].[XYZW]}}, {{T[0-9].[XYZW]}}, literal
+; EG-DAG: AND_INT {{[* ]*}}T{{[0-9].[XYZW]}}, {{T[0-9].[XYZW]}}, literal
; EG-DAG: 16
define void @constant_constant_zextload_v4i16_to_v4i32(<4 x i32> addrspace(1)* %out, <4 x i16> addrspace(2)* %in) #0 {
%load = load <4 x i16>, <4 x i16> addrspace(2)* %in
Modified: llvm/trunk/test/CodeGen/AMDGPU/load-global-i16.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AMDGPU/load-global-i16.ll?rev=280927&r1=280926&r2=280927&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AMDGPU/load-global-i16.ll (original)
+++ llvm/trunk/test/CodeGen/AMDGPU/load-global-i16.ll Thu Sep 8 07:57:51 2016
@@ -147,7 +147,7 @@ define void @global_sextload_v1i16_to_v1
; EG: VTX_READ_32 [[DST:T[0-9]\.[XYZW]]], [[DST]], 0, #1
; TODO: This should use DST, but for some there are redundant MOVs
-; EG: LSHR {{[* ]*}}T{{[0-9].[XYZW]}}, {{PV.[XYZW]}}, literal
+; EG: BFE_UINT {{[* ]*}}T{{[0-9].[XYZW]}}, {{PV.[XYZW]}}, literal
; EG: 16
define void @global_zextload_v2i16_to_v2i32(<2 x i32> addrspace(1)* %out, <2 x i16> addrspace(1)* %in) #0 {
%load = load <2 x i16>, <2 x i16> addrspace(1)* %in
@@ -219,9 +219,10 @@ entry:
; EG: VTX_READ_64 [[DST:T[0-9]\.XY]], {{T[0-9].[XYZW]}}, 0, #1
; TODO: These should use DST, but for some there are redundant MOVs
-; EG-DAG: LSHR {{[* ]*}}T{{[0-9].[XYZW]}}, {{PV.[XYZW]}}, literal
-; EG-DAG: LSHR {{[* ]*}}T{{[0-9].[XYZW]}}, {{T[0-9].[XYZW]}}, literal
+; EG-DAG: BFE_UINT {{[* ]*}}T{{[0-9].[XYZW]}}, {{T[0-9].[XYZW]}}, literal
; EG-DAG: 16
+; EG-DAG: BFE_UINT {{[* ]*}}T{{[0-9].[XYZW]}}, {{T[0-9].[XYZW]}}, literal
+; EG-DAG: AND_INT {{[* ]*}}T{{[0-9].[XYZW]}}, {{T[0-9].[XYZW]}}, literal
; EG-DAG: 16
define void @global_global_zextload_v4i16_to_v4i32(<4 x i32> addrspace(1)* %out, <4 x i16> addrspace(1)* %in) #0 {
%load = load <4 x i16>, <4 x i16> addrspace(1)* %in
Modified: llvm/trunk/test/CodeGen/X86/combine-and.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/combine-and.ll?rev=280927&r1=280926&r2=280927&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/combine-and.ll (original)
+++ llvm/trunk/test/CodeGen/X86/combine-and.ll Thu Sep 8 07:57:51 2016
@@ -210,10 +210,7 @@ define <4 x i32> @and_or_v4i32(<4 x i32>
define <2 x i64> @and_or_zext_v2i32(<2 x i32> %a0) {
; CHECK-LABEL: and_or_zext_v2i32:
; CHECK: # BB#0:
-; CHECK-NEXT: pxor %xmm1, %xmm1
-; CHECK-NEXT: pblendw {{.*#+}} xmm0 = xmm0[0,1],xmm1[2,3],xmm0[4,5],xmm1[6,7]
-; CHECK-NEXT: por {{.*}}(%rip), %xmm0
-; CHECK-NEXT: pand {{.*}}(%rip), %xmm0
+; CHECK-NEXT: xorps %xmm0, %xmm0
; CHECK-NEXT: retq
%1 = zext <2 x i32> %a0 to <2 x i64>
%2 = or <2 x i64> %1, <i64 1, i64 1>
@@ -224,10 +221,7 @@ define <2 x i64> @and_or_zext_v2i32(<2 x
define <4 x i32> @and_or_zext_v4i16(<4 x i16> %a0) {
; CHECK-LABEL: and_or_zext_v4i16:
; CHECK: # BB#0:
-; CHECK-NEXT: pxor %xmm1, %xmm1
-; CHECK-NEXT: pblendw {{.*#+}} xmm0 = xmm0[0],xmm1[1],xmm0[2],xmm1[3],xmm0[4],xmm1[5],xmm0[6],xmm1[7]
-; CHECK-NEXT: por {{.*}}(%rip), %xmm0
-; CHECK-NEXT: pand {{.*}}(%rip), %xmm0
+; CHECK-NEXT: xorps %xmm0, %xmm0
; CHECK-NEXT: retq
%1 = zext <4 x i16> %a0 to <4 x i32>
%2 = or <4 x i32> %1, <i32 1, i32 1, i32 1, i32 1>
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