[llvm] r371078 - [X86][SSE] EltsFromConsecutiveLoads - ignore non-zero offset base loads (PR43227)

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Thu Sep  5 08:07:07 2019
New Revision: 371078

URL: http://llvm.org/viewvc/llvm-project?rev=371078&view=rev
Log:
[X86][SSE] EltsFromConsecutiveLoads - ignore non-zero offset base loads (PR43227)

As discussed on D64551 and PR43227, we don't correctly handle cases where the base load has a non-zero byte offset.

Until we can properly handle this, we must bail from EltsFromConsecutiveLoads.

Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
    llvm/trunk/test/CodeGen/X86/load-partial.ll

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=371078&r1=371077&r2=371078&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Thu Sep  5 08:07:07 2019
@@ -7719,6 +7719,10 @@ static SDValue EltsFromConsecutiveLoads(
   int LoadSizeInBits = (1 + LastLoadedElt - FirstLoadedElt) * BaseSizeInBits;
   assert((BaseSizeInBits % 8) == 0 && "Sub-byte element loads detected");
 
+  // TODO: Support offsetting the base load.
+  if (ByteOffsets[FirstLoadedElt] != 0)
+    return SDValue();
+
   // Check to see if the element's load is consecutive to the base load
   // or offset from a previous (already checked) load.
   auto CheckConsecutiveLoad = [&](LoadSDNode *Base, int EltIdx) {

Modified: llvm/trunk/test/CodeGen/X86/load-partial.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/load-partial.ll?rev=371078&r1=371077&r2=371078&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/load-partial.ll (original)
+++ llvm/trunk/test/CodeGen/X86/load-partial.ll Thu Sep  5 08:07:07 2019
@@ -374,19 +374,24 @@ define void @PR43227(i32* %explicit_0, <
 ;
 ; SSE41-LABEL: PR43227:
 ; SSE41:       # %bb.0:
-; SSE41-NEXT:    movss {{.*#+}} xmm0 = mem[0],zero,zero,zero
-; SSE41-NEXT:    movss {{.*#+}} xmm1 = mem[0],zero,zero,zero
-; SSE41-NEXT:    movlhps {{.*#+}} xmm1 = xmm1[0],xmm0[0]
-; SSE41-NEXT:    xorps %xmm0, %xmm0
-; SSE41-NEXT:    movaps %xmm0, 672(%rsi)
-; SSE41-NEXT:    movaps %xmm1, 688(%rsi)
+; SSE41-NEXT:    movq {{.*#+}} xmm0 = mem[0],zero
+; SSE41-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[1,1,2,3]
+; SSE41-NEXT:    pxor %xmm1, %xmm1
+; SSE41-NEXT:    pblendw {{.*#+}} xmm0 = xmm0[0,1],xmm1[2,3,4,5,6,7]
+; SSE41-NEXT:    movd {{.*#+}} xmm2 = mem[0],zero,zero,zero
+; SSE41-NEXT:    punpcklqdq {{.*#+}} xmm0 = xmm0[0],xmm2[0]
+; SSE41-NEXT:    movdqa %xmm1, 672(%rsi)
+; SSE41-NEXT:    movdqa %xmm0, 688(%rsi)
 ; SSE41-NEXT:    retq
 ;
 ; AVX-LABEL: PR43227:
 ; AVX:       # %bb.0:
-; AVX-NEXT:    vmovss {{.*#+}} xmm0 = mem[0],zero,zero,zero
+; AVX-NEXT:    vmovsd {{.*#+}} xmm0 = mem[0],zero
+; AVX-NEXT:    vpermilps {{.*#+}} xmm0 = xmm0[1,1,2,3]
+; AVX-NEXT:    vxorps %xmm1, %xmm1, %xmm1
+; AVX-NEXT:    vblendps {{.*#+}} xmm0 = xmm0[0],xmm1[1,2,3]
 ; AVX-NEXT:    vmovss {{.*#+}} xmm1 = mem[0],zero,zero,zero
-; AVX-NEXT:    vmovlhps {{.*#+}} xmm0 = xmm1[0],xmm0[0]
+; AVX-NEXT:    vmovlhps {{.*#+}} xmm0 = xmm0[0],xmm1[0]
 ; AVX-NEXT:    vxorps %xmm1, %xmm1, %xmm1
 ; AVX-NEXT:    vinsertf128 $1, %xmm0, %ymm1, %ymm0
 ; AVX-NEXT:    vmovaps %ymm0, 672(%rsi)