[llvm] r223922 - [X86] Make a code path in EltsFromConsecutiveLoads work only on vectors it expects

[Michael Kuperstein]

Author: mkuper
Date: Wed Dec 10 02:46:12 2014
New Revision: 223922

URL: http://llvm.org/viewvc/llvm-project?rev=223922&view=rev
Log:
[X86] Make a code path in EltsFromConsecutiveLoads work only on vectors it expects

EltsFromConsecutiveLoads was apparently only ever called for 128-bit vectors, and assumed this implicitly. r223518 started calling it for AVX-sized vectors, causing the code path that had this assumption to crash.
This adds a check to make this path fire only for 128-bit vectors.

Differential Revision: http://reviews.llvm.org/D6579

Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
    llvm/trunk/test/CodeGen/X86/vec_loadsingles.ll

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=223922&r1=223921&r2=223922&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Wed Dec 10 02:46:12 2014
@@ -6023,7 +6023,10 @@ static SDValue EltsFromConsecutiveLoads(
 
     return NewLd;
   }
-  if (NumElems == 4 && LastLoadedElt == 1 &&
+  
+  //TODO: The code below fires only for for loading the low v2i32 / v2f32
+  //of a v4i32 / v4f32. It's probably worth generalizing.
+  if (NumElems == 4 && LastLoadedElt == 1 && (EltVT.getSizeInBits() == 32) &&
       DAG.getTargetLoweringInfo().isTypeLegal(MVT::v2i64)) {
     SDVTList Tys = DAG.getVTList(MVT::v2i64, MVT::Other);
     SDValue Ops[] = { LDBase->getChain(), LDBase->getBasePtr() };

Modified: llvm/trunk/test/CodeGen/X86/vec_loadsingles.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/vec_loadsingles.ll?rev=223922&r1=223921&r2=223922&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/vec_loadsingles.ll (original)
+++ llvm/trunk/test/CodeGen/X86/vec_loadsingles.ll Wed Dec 10 02:46:12 2014
@@ -14,6 +14,25 @@ define <4 x float> @merge_2_floats(float
 ; ALL-NEXT: retq
 }
 
+; Test-case generated due to a crash when trying to treat loading the first
+; two i64s of a <4 x i64> as a load of two i32s.
+define <4 x i64> @merge_2_floats_into_4() {
+  %1 = load i64** undef, align 8
+  %2 = getelementptr inbounds i64* %1, i64 0
+  %3 = load i64* %2
+  %4 = insertelement <4 x i64> undef, i64 %3, i32 0
+  %5 = load i64** undef, align 8
+  %6 = getelementptr inbounds i64* %5, i64 1
+  %7 = load i64* %6
+  %8 = insertelement <4 x i64> %4, i64 %7, i32 1
+  %9 = shufflevector <4 x i64> %8, <4 x i64> undef, <4 x i32> <i32 0, i32 1, i32 4, i32 5>
+  ret <4 x i64> %9
+  
+; ALL-LABEL: merge_2_floats_into_4
+; ALL: vmovups
+; ALL-NEXT: retq
+}
+
 define <4 x float> @merge_4_floats(float* %ptr) {
   %a = load float* %ptr, align 8
   %vec = insertelement <4 x float> undef, float %a, i32 0