[X86] getTargetConstantBitsFromNode - early-out if the element bitsize doesn't align with the source bitsize

[RKSimon]

As we use getTargetConstantBitsFromNode in a wider variety of places we can't guarantee that all the sources match (or are legal) anymore - better to early out than assert.

Fixes #150117

[llvmbot]

@llvm/pr-subscribers-backend-x86

Author: Simon Pilgrim (RKSimon)

Changes

As we use getTargetConstantBitsFromNode in a wider variety of places we can't guarantee that all the sources match (or are legal) anymore - better to early out than assert.

Fixes #150117

---

Full diff: https://github.com/llvm/llvm-project/pull/150184.diff

2 Files Affected:

• (modified) llvm/lib/Target/X86/X86ISelLowering.cpp (+4-1)
• (modified) llvm/test/CodeGen/X86/vec_extract.ll (+66)

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 568a8c4cfed79..11ab8dc685ea8 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -5001,9 +5001,12 @@ static bool getTargetConstantBitsFromNode(SDValue Op, unsigned EltSizeInBits,
 
   EVT VT = Op.getValueType();
   unsigned SizeInBits = VT.getSizeInBits();
-  assert((SizeInBits % EltSizeInBits) == 0 && "Can't split constant!");
   unsigned NumElts = SizeInBits / EltSizeInBits;
 
+  // Can't split constant.
+  if ((SizeInBits % EltSizeInBits) != 0)
+    return false;
+
   // Bitcast a source array of element bits to the target size.
   auto CastBitData = [&](APInt &UndefSrcElts, ArrayRef<APInt> SrcEltBits) {
     unsigned NumSrcElts = UndefSrcElts.getBitWidth();
diff --git a/llvm/test/CodeGen/X86/vec_extract.ll b/llvm/test/CodeGen/X86/vec_extract.ll
index 087cd30abee9b..9bd38db3e9c4c 100644
--- a/llvm/test/CodeGen/X86/vec_extract.ll
+++ b/llvm/test/CodeGen/X86/vec_extract.ll
@@ -104,6 +104,72 @@ entry:
 }
 declare <2 x double> @foo()
 
+define i64 @pr150117(<31 x i8> %a0) nounwind {
+; X86-LABEL: pr150117:
+; X86:       # %bb.0:
+; X86-NEXT:    pushl %ebx
+; X86-NEXT:    pushl %edi
+; X86-NEXT:    pushl %esi
+; X86-NEXT:    movzbl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movzbl {{[0-9]+}}(%esp), %ecx
+; X86-NEXT:    movzbl {{[0-9]+}}(%esp), %esi
+; X86-NEXT:    movzbl {{[0-9]+}}(%esp), %edi
+; X86-NEXT:    movzbl {{[0-9]+}}(%esp), %ebx
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %edx
+; X86-NEXT:    shll $8, %edx
+; X86-NEXT:    orl %ebx, %edx
+; X86-NEXT:    shll $8, %edi
+; X86-NEXT:    orl %esi, %edi
+; X86-NEXT:    shll $16, %ecx
+; X86-NEXT:    orl %edi, %ecx
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %esi
+; X86-NEXT:    shll $24, %esi
+; X86-NEXT:    orl %ecx, %esi
+; X86-NEXT:    movd %esi, %xmm0
+; X86-NEXT:    pinsrw $2, %edx, %xmm0
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %ecx
+; X86-NEXT:    shll $8, %ecx
+; X86-NEXT:    orl %eax, %ecx
+; X86-NEXT:    pinsrw $3, %ecx, %xmm0
+; X86-NEXT:    movd %xmm0, %eax
+; X86-NEXT:    pshufd {{.*#+}} xmm0 = xmm0[1,1,1,1]
+; X86-NEXT:    movd %xmm0, %edx
+; X86-NEXT:    popl %esi
+; X86-NEXT:    popl %edi
+; X86-NEXT:    popl %ebx
+; X86-NEXT:    retl
+;
+; X64-LABEL: pr150117:
+; X64:       # %bb.0:
+; X64-NEXT:    movzbl {{[0-9]+}}(%rsp), %eax
+; X64-NEXT:    movzbl {{[0-9]+}}(%rsp), %ecx
+; X64-NEXT:    movzbl {{[0-9]+}}(%rsp), %edx
+; X64-NEXT:    movzbl {{[0-9]+}}(%rsp), %esi
+; X64-NEXT:    movzbl {{[0-9]+}}(%rsp), %edi
+; X64-NEXT:    movl {{[0-9]+}}(%rsp), %r8d
+; X64-NEXT:    shll $8, %r8d
+; X64-NEXT:    orl %edi, %r8d
+; X64-NEXT:    shll $8, %esi
+; X64-NEXT:    orl %edx, %esi
+; X64-NEXT:    shll $16, %ecx
+; X64-NEXT:    orl %esi, %ecx
+; X64-NEXT:    movl {{[0-9]+}}(%rsp), %edx
+; X64-NEXT:    shll $24, %edx
+; X64-NEXT:    orl %ecx, %edx
+; X64-NEXT:    movd %edx, %xmm0
+; X64-NEXT:    pinsrw $2, %r8d, %xmm0
+; X64-NEXT:    movl {{[0-9]+}}(%rsp), %ecx
+; X64-NEXT:    shll $8, %ecx
+; X64-NEXT:    orl %eax, %ecx
+; X64-NEXT:    pinsrw $3, %ecx, %xmm0
+; X64-NEXT:    movq %xmm0, %rax
+; X64-NEXT:    retq
+  %shuffle = shufflevector <31 x i8> %a0, <31 x i8> zeroinitializer, <32 x i32> <i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison, i32 poison>
+  %bitcast = bitcast <32 x i8> %shuffle to <4 x i64>
+  %elt = extractelement <4 x i64> %bitcast, i64 0
+  ret i64 %elt
+}
+
 ; OSS-Fuzz #15662
 ; https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=15662
 define <4 x i32> @ossfuzz15662(ptr %in) {

[phoebewang]

LGTM.