[llvm] [X86][EVEX512] Do not allow 512-bit memcpy without EVEX512 (PR #70420)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-x86

Author: Phoebe Wang (phoebewang)

<details>
<summary>Changes</summary>

Solves crash mentioned in #<!-- -->65920.

---
Full diff: https://github.com/llvm/llvm-project/pull/70420.diff


2 Files Affected:

- (modified) llvm/lib/Target/X86/X86ISelLoweringCall.cpp (+2-2) 
- (added) llvm/test/CodeGen/X86/evex512-mem.ll (+29) 


``````````diff
diff --git a/llvm/lib/Target/X86/X86ISelLoweringCall.cpp b/llvm/lib/Target/X86/X86ISelLoweringCall.cpp
index c47ddae072b4fe8..2fe145f9267de87 100644
--- a/llvm/lib/Target/X86/X86ISelLoweringCall.cpp
+++ b/llvm/lib/Target/X86/X86ISelLoweringCall.cpp
@@ -281,7 +281,7 @@ EVT X86TargetLowering::getOptimalMemOpType(
     if (Op.size() >= 16 &&
         (!Subtarget.isUnalignedMem16Slow() || Op.isAligned(Align(16)))) {
       // FIXME: Check if unaligned 64-byte accesses are slow.
-      if (Op.size() >= 64 && Subtarget.hasAVX512() &&
+      if (Op.size() >= 64 && Subtarget.hasAVX512() && Subtarget.hasEVEX512() &&
           (Subtarget.getPreferVectorWidth() >= 512)) {
         return Subtarget.hasBWI() ? MVT::v64i8 : MVT::v16i32;
       }
@@ -395,7 +395,7 @@ bool X86TargetLowering::allowsMemoryAccess(LLVMContext &Context,
         return true;
       return false;
     case 512:
-      if (Subtarget.hasAVX512())
+      if (Subtarget.hasAVX512() && Subtarget.hasEVEX512())
         return true;
       return false;
     default:
diff --git a/llvm/test/CodeGen/X86/evex512-mem.ll b/llvm/test/CodeGen/X86/evex512-mem.ll
new file mode 100644
index 000000000000000..a900d0837c1baa3
--- /dev/null
+++ b/llvm/test/CodeGen/X86/evex512-mem.ll
@@ -0,0 +1,29 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=x86_64-apple-darwin -mattr=avx512f,avx512bw,avx512vl < %s | FileCheck %s --check-prefix=AVX512
+; RUN: llc -mtriple=x86_64-apple-darwin -mattr=avx512f,avx512bw,avx512vl,-evex512 < %s | FileCheck %s --check-prefix=AVX256
+
+define void @test1() {
+; AVX512-LABEL: test1:
+; AVX512:       ## %bb.0:
+; AVX512-NEXT:    movq 64, %rax
+; AVX512-NEXT:    movq %rax, (%rax)
+; AVX512-NEXT:    vmovups 0, %zmm0
+; AVX512-NEXT:    vmovups %zmm0, (%rax)
+; AVX512-NEXT:    vzeroupper
+; AVX512-NEXT:    retq
+;
+; AVX256-LABEL: test1:
+; AVX256:       ## %bb.0:
+; AVX256-NEXT:    movq 64, %rax
+; AVX256-NEXT:    movq %rax, (%rax)
+; AVX256-NEXT:    vmovups 0, %ymm0
+; AVX256-NEXT:    vmovups 32, %ymm1
+; AVX256-NEXT:    vmovups %ymm1, (%rax)
+; AVX256-NEXT:    vmovups %ymm0, (%rax)
+; AVX256-NEXT:    vzeroupper
+; AVX256-NEXT:    retq
+  call void @llvm.memcpy.p0.p0.i64(ptr align 8 poison, ptr align 8 null, i64 72, i1 false)
+  ret void
+}
+
+declare void @llvm.memcpy.p0.p0.i64(ptr, ptr, i64, i1)

``````````

</details>


https://github.com/llvm/llvm-project/pull/70420