[PATCH] Teach the DAGCombiner how to fold concat_vector nodes when the input is two BUILD_VECTOR nodes.
Robert Lougher
rob.lougher at gmail.com
Tue Jan 28 09:40:52 PST 2014
Hi,
This patch teaches the DAGCombiner how to fold concat_vector nodes
when the input is two BUILD_VECTOR nodes, e.g.:
(concat_vectors (BUILD_VECTOR a1, a2, a3, a4), (BUILD_VECTOR b1, b2, b3, b4))
->
(BUILD_VECTOR a1, a2, a3, a4, b1, b2, b3, b4)
This can be seen with the following IR:
define <8 x float> @memory4(float* %p) {
%1 = load float* %p, align 4
%2 = insertelement <4 x float> undef, float %1, i32 0
%3 = insertelement <4 x float> %2, float %1, i32 1
%4 = insertelement <4 x float> %3, float %1, i32 2
%5 = insertelement <4 x float> %4, float %1, i32 3
%6 = shufflevector <4 x float> %5, <4 x float> undef, <8 x i32> <i32
0, i32 1, i32 2, i32 3, i32 0, i32 1, i32 2, i32 3>
The shufflevector is turned into a concat_vectors node, and the
insertelements into a BUILD_VECTOR.
On AVX, without the patch this generates two instructions:
vbroadcastss (%rdi), %xmm0
vinsertf128 $1, %xmm0, %ymm0, %ymm0
With the patch:
vbroadcastss (%rdi), %ymm0
This is because the whole sequence was not recognized as a 256-bit
vbroadcast by LowerVectorBroadcast (X86ISelLowering.cpp) due to the
concat_vectors.
I have added tests to avx-vbroadcast.ll and avx2-vbroadcast.ll that
check both single and double vbroadcasts. If the patch looks OK
please submit for me.
Thanks,
Rob.
--
Robert Lougher
SN Systems - Sony Computer Entertainment Group
-------------- next part --------------
Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp (revision 200319)
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp (working copy)
@@ -10125,6 +10125,26 @@
}
}
+ // fold (concat_vectors (BUILD_VECTOR A, B, ...), (BUILD_VECTOR C, D, ...))
+ // -> (BUILD_VECTOR A, B, ..., C, D, ...)
+ if (N->getNumOperands() == 2 &&
+ N->getOperand(0).getOpcode() == ISD::BUILD_VECTOR &&
+ N->getOperand(1).getOpcode() == ISD::BUILD_VECTOR) {
+ EVT VT = N->getValueType(0);
+ SDValue N0 = N->getOperand(0);
+ SDValue N1 = N->getOperand(1);
+ SmallVector<SDValue, 8> Opnds;
+ unsigned BuildVecNumElts = N0.getNumOperands();
+
+ for (unsigned i = 0; i != BuildVecNumElts; ++i)
+ Opnds.push_back(N0.getOperand(i));
+ for (unsigned i = 0; i != BuildVecNumElts; ++i)
+ Opnds.push_back(N1.getOperand(i));
+
+ return DAG.getNode(ISD::BUILD_VECTOR, SDLoc(N), VT, &Opnds[0],
+ Opnds.size());
+ }
+
// Type legalization of vectors and DAG canonicalization of SHUFFLE_VECTOR
// nodes often generate nop CONCAT_VECTOR nodes.
// Scan the CONCAT_VECTOR operands and look for a CONCAT operations that
Index: test/CodeGen/X86/avx2-vbroadcast.ll
===================================================================
--- test/CodeGen/X86/avx2-vbroadcast.ll (revision 200319)
+++ test/CodeGen/X86/avx2-vbroadcast.ll (working copy)
@@ -355,3 +355,61 @@
%b = shufflevector <16 x i8> %a, <16 x i8> undef, <16 x i32> zeroinitializer
ret <16 x i8> %b
}
+
+; These tests check that a vbroadcast instruction is used when we have a splat
+; formed from a concat_vectors (via the shufflevector) of two BUILD_VECTORs
+; (via the insertelements).
+
+; CHECK-LABEL: splat_concat1
+; CHECK-NOT: vinsertf128
+; CHECK: vbroadcastss
+; CHECK-NEXT: ret
+define <8 x float> @splat_concat1(float %f) {
+ %1 = insertelement <4 x float> undef, float %f, i32 0
+ %2 = insertelement <4 x float> %1, float %f, i32 1
+ %3 = insertelement <4 x float> %2, float %f, i32 2
+ %4 = insertelement <4 x float> %3, float %f, i32 3
+ %5 = shufflevector <4 x float> %4, <4 x float> undef, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 0, i32 1, i32 2, i32 3>
+ ret <8 x float> %5
+}
+
+; CHECK-LABEL: splat_concat2
+; CHECK-NOT: vinsertf128
+; CHECK: vbroadcastss
+; CHECK-NEXT: ret
+define <8 x float> @splat_concat2(float %f) {
+ %1 = insertelement <4 x float> undef, float %f, i32 0
+ %2 = insertelement <4 x float> %1, float %f, i32 1
+ %3 = insertelement <4 x float> %2, float %f, i32 2
+ %4 = insertelement <4 x float> %3, float %f, i32 3
+ %5 = insertelement <4 x float> undef, float %f, i32 0
+ %6 = insertelement <4 x float> %5, float %f, i32 1
+ %7 = insertelement <4 x float> %6, float %f, i32 2
+ %8 = insertelement <4 x float> %7, float %f, i32 3
+ %9 = shufflevector <4 x float> %4, <4 x float> %8, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
+ ret <8 x float> %9
+}
+
+; CHECK-LABEL: splat_concat3
+; CHECK-NOT: vinsertf128
+; CHECK: vbroadcastsd
+; CHECK-NEXT: ret
+define <4 x double> @splat_concat3(double %d) {
+ %1 = insertelement <2 x double> undef, double %d, i32 0
+ %2 = insertelement <2 x double> %1, double %d, i32 1
+ %3 = shufflevector <2 x double> %2, <2 x double> undef, <4 x i32> <i32 0, i32 1, i32 0, i32 1>
+ ret <4 x double> %3
+}
+
+; CHECK-LABEL: splat_concat4
+; CHECK-NOT: vinsertf128
+; CHECK: vbroadcastsd
+; CHECK-NEXT: ret
+define <4 x double> @splat_concat4(double %d) {
+ %1 = insertelement <2 x double> undef, double %d, i32 0
+ %2 = insertelement <2 x double> %1, double %d, i32 1
+ %3 = insertelement <2 x double> undef, double %d, i32 0
+ %4 = insertelement <2 x double> %3, double %d, i32 1
+ %5 = shufflevector <2 x double> %2, <2 x double> %4, <4 x i32> <i32 0, i32 1, i32 2, i32 3>
+ ret <4 x double> %5
+}
Index: test/CodeGen/X86/avx-vbroadcast.ll
===================================================================
--- test/CodeGen/X86/avx-vbroadcast.ll (revision 200319)
+++ test/CodeGen/X86/avx-vbroadcast.ll (working copy)
@@ -141,3 +141,66 @@
ret <4 x float> %t
}
+
+; These tests check that a vbroadcast instruction is used when we have a splat
+; formed from a concat_vectors (via the shufflevector) of two BUILD_VECTORs
+; (via the insertelements).
+
+; CHECK-LABEL: splat_concat1
+; CHECK-NOT: vinsertf128
+; CHECK: vbroadcastss (%
+; CHECK-NEXT: ret
+define <8 x float> @splat_concat1(float* %p) {
+ %1 = load float* %p, align 4
+ %2 = insertelement <4 x float> undef, float %1, i32 0
+ %3 = insertelement <4 x float> %2, float %1, i32 1
+ %4 = insertelement <4 x float> %3, float %1, i32 2
+ %5 = insertelement <4 x float> %4, float %1, i32 3
+ %6 = shufflevector <4 x float> %5, <4 x float> undef, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 0, i32 1, i32 2, i32 3>
+ ret <8 x float> %6
+}
+
+; CHECK-LABEL: splat_concat2
+; CHECK-NOT: vinsertf128
+; CHECK: vbroadcastss (%
+; CHECK-NEXT: ret
+define <8 x float> @splat_concat2(float* %p) {
+ %1 = load float* %p, align 4
+ %2 = insertelement <4 x float> undef, float %1, i32 0
+ %3 = insertelement <4 x float> %2, float %1, i32 1
+ %4 = insertelement <4 x float> %3, float %1, i32 2
+ %5 = insertelement <4 x float> %4, float %1, i32 3
+ %6 = insertelement <4 x float> undef, float %1, i32 0
+ %7 = insertelement <4 x float> %6, float %1, i32 1
+ %8 = insertelement <4 x float> %7, float %1, i32 2
+ %9 = insertelement <4 x float> %8, float %1, i32 3
+ %10 = shufflevector <4 x float> %5, <4 x float> %9, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>
+ ret <8 x float> %10
+}
+
+; CHECK-LABEL: splat_concat3
+; CHECK-NOT: vinsertf128
+; CHECK: vbroadcastsd (%
+; CHECK-NEXT: ret
+define <4 x double> @splat_concat3(double* %p) {
+ %1 = load double* %p, align 8
+ %2 = insertelement <2 x double> undef, double %1, i32 0
+ %3 = insertelement <2 x double> %2, double %1, i32 1
+ %4 = shufflevector <2 x double> %3, <2 x double> undef, <4 x i32> <i32 0, i32 1, i32 0, i32 1>
+ ret <4 x double> %4
+}
+
+; CHECK-LABEL: splat_concat4
+; CHECK-NOT: vinsertf128
+; CHECK: vbroadcastsd (%
+; CHECK-NEXT: ret
+define <4 x double> @splat_concat4(double* %p) {
+ %1 = load double* %p, align 8
+ %2 = insertelement <2 x double> undef, double %1, i32 0
+ %3 = insertelement <2 x double> %2, double %1, i32 1
+ %4 = insertelement <2 x double> undef, double %1, i32 0
+ %5 = insertelement <2 x double> %2, double %1, i32 1
+ %6 = shufflevector <2 x double> %3, <2 x double> %5, <4 x i32> <i32 0, i32 1, i32 2, i32 3>
+ ret <4 x double> %6
+}
+
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