[PATCH] Fix VGATHER* operand constraints

Add earlyclobber constaints to prevent input register being allocated as
the output register because, according to Intel spec [1], "If any pair
of the index, mask, or destination registers are the same, this
instruction results a UD fault."

---
[1] http://software.intel.com/sites/default/files/319433-014.pdf

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183327 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelDAGToDAG.cpp b/lib/Target/X86/X86ISelDAGToDAG.cpp
index 02f5fe495254633d870faebfbf76a8a2b3bd4f3a..14ec2ddb4ec697e2270dcbd00d3edc12bd187bdc 100644 (file)
--- a/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ b/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -2041,6 +2041,8 @@ SDNode *X86DAGToDAGISel::Select(SDNode *Node) {
     case Intrinsic::x86_avx2_gather_d_d_256:
     case Intrinsic::x86_avx2_gather_q_d:
     case Intrinsic::x86_avx2_gather_q_d_256: {
+      if (!Subtarget->hasAVX2())
+        break;
       unsigned Opc;
       switch (IntNo) {
       default: llvm_unreachable("Impossible intrinsic");

diff --git a/lib/Target/X86/X86InstrSSE.td b/lib/Target/X86/X86InstrSSE.td
index cce7788fb3dbe485f8716fb2459f3e093012ea84..a1d3e813119bcf734f2a8697658d27c3d7440b93 100644 (file)
--- a/lib/Target/X86/X86InstrSSE.td
+++ b/lib/Target/X86/X86InstrSSE.td
@@ -8372,7 +8372,9 @@ multiclass avx2_gather<bits<8> opc, string OpcodeStr, RegisterClass RC256,
             []>, VEX_4VOp3, VEX_L;
 }
 
-let mayLoad = 1, Constraints = "$src1 = $dst, $mask = $mask_wb" in {
+let mayLoad = 1, Constraints
+  = "@earlyclobber $dst,@earlyclobber $mask_wb, $src1 = $dst, $mask = $mask_wb"
+  in {
   defm VGATHERDPD : avx2_gather<0x92, "vgatherdpd", VR256, vx64mem, vx64mem>, VEX_W;
   defm VGATHERQPD : avx2_gather<0x93, "vgatherqpd", VR256, vx64mem, vy64mem>, VEX_W;
   defm VGATHERDPS : avx2_gather<0x92, "vgatherdps", VR256, vx32mem, vy32mem>;

diff --git a/test/CodeGen/X86/avx2-gather.ll b/test/CodeGen/X86/avx2-gather.ll
new file mode 100644 (file)
index 0000000..ee50c45
--- /dev/null
+++ b/test/CodeGen/X86/avx2-gather.ll
@@ -0,0 +1,18 @@
+; RUN: not llc < %s -mtriple=x86_64-apple-darwin -mcpu=corei7-avx
+; RUN: llc < %s -mtriple=x86_64-apple-darwin -mcpu=core-avx2 | FileCheck %s
+
+declare <4 x float> @llvm.x86.avx2.gather.d.ps(<4 x float>, i8*,
+                      <4 x i32>, <4 x float>, i8) nounwind readonly
+
+define <4 x float> @test_x86_avx2_gather_d_ps(i8* %a1,
+                     <4 x i32> %idx, <4 x float> %mask) {
+  %res = call <4 x float> @llvm.x86.avx2.gather.d.ps(<4 x float> undef,
+                            i8* %a1, <4 x i32> %idx, <4 x float> %mask, i8 2) ;
+  ret <4 x float> %res
+}
+
+; CHECK: test_x86_avx2_gather_d_ps
+; CHECK: vgatherdps
+; CHECK-NOT: [[DST]]
+; CHECK: [[DST:%xmm[0-9]+]]{{$}}
+; CHECK: ret