[llvm] [WIP][SelectionDAG] Add support for the 3-way comparison intrinsics [US]CMP (PR #91871)

[Nikita Popov via llvm-commits]

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@@ -0,0 +1,498 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 4
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s
+
+define i8 @ucmp(i32 %x, i32 %y) {
+; CHECK-LABEL: ucmp:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    xorl %ecx, %ecx
+; CHECK-NEXT:    cmpl %esi, %edi
+; CHECK-NEXT:    seta %cl
+; CHECK-NEXT:    movl $255, %eax
+; CHECK-NEXT:    cmovael %ecx, %eax
+; CHECK-NEXT:    # kill: def $al killed $al killed $eax
+; CHECK-NEXT:    retq
+  %1 = call i8 @llvm.ucmp(i32 %x, i32 %y)
+  ret i8 %1
+}
+
+define i8 @scmp(i32 %x, i32 %y) {
+; CHECK-LABEL: scmp:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    xorl %ecx, %ecx
+; CHECK-NEXT:    cmpl %esi, %edi
+; CHECK-NEXT:    seta %cl
+; CHECK-NEXT:    movl $255, %eax
+; CHECK-NEXT:    cmovael %ecx, %eax
+; CHECK-NEXT:    # kill: def $al killed $al killed $eax
+; CHECK-NEXT:    retq
+  %1 = call i8 @llvm.ucmp(i32 %x, i32 %y)
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nikic wrote:

Some of your `@scmp` tests actually use ucmp :)

I'd probably split these into separate files entirely.

https://github.com/llvm/llvm-project/pull/91871