[llvm] [X86][CodeGen] Support using NF instructions for flag copy lowering (PR #93508)

[Shengchen Kan via llvm-commits]

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@@ -0,0 +1,90 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+nf | FileCheck %s
+
+define i32 @flag_copy_1(i32 %x, i32 %y, ptr %pz) nounwind {
+; CHECK-LABEL: flag_copy_1:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    movq %rdx, %rcx
+; CHECK-NEXT:    movl %edi, %eax
+; CHECK-NEXT:    mull %esi
+; CHECK-NEXT:    movl (%rcx), %ecx
+; CHECK-NEXT:    {nf} addl %eax, %ecx
+; CHECK-NEXT:    cmovol %ecx, %eax
+; CHECK-NEXT:    retq
+  %o = tail call { i32, i1 } @llvm.umul.with.overflow.i32(i32 %x, i32 %y)
+  %v1 = extractvalue { i32, i1 } %o, 1
+  %v2 = extractvalue { i32, i1 } %o, 0
+  %z = load i32, ptr %pz
+  %a = add i32 %v2, %z
+  %r = select i1 %v1, i32 %a, i32 %v2
+  ret i32 %r
+}
+
+declare <2 x i128> @llvm.ssub.sat.v2i128(<2 x i128>, <2 x i128>)
+
+define <2 x i128> @flag_copy_2(<2 x i128> %x, <2 x i128> %y) nounwind {
+; CHECK-LABEL: flag_copy_2:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    movq %rdi, %rax
+; CHECK-NEXT:    subq {{[0-9]+}}(%rsp), %rcx
+; CHECK-NEXT:    sbbq {{[0-9]+}}(%rsp), %r8
+; CHECK-NEXT:    movq %r8, %rdi
+; CHECK-NEXT:    {nf} sarq $63, %rdi
+; CHECK-NEXT:    cmovoq %rdi, %rcx
+; CHECK-NEXT:    movabsq $-9223372036854775808, %r9 # imm = 0x8000000000000000
+; CHECK-NEXT:    {nf} xorq %r9, %rdi
+; CHECK-NEXT:    cmovnoq %r8, %rdi
+; CHECK-NEXT:    subq {{[0-9]+}}(%rsp), %rsi
+; CHECK-NEXT:    sbbq {{[0-9]+}}(%rsp), %rdx
+; CHECK-NEXT:    movq %rdx, %r8
+; CHECK-NEXT:    {nf} sarq $63, %r8
+; CHECK-NEXT:    cmovoq %r8, %rsi
+; CHECK-NEXT:    {nf} xorq %r9, %r8
+; CHECK-NEXT:    cmovnoq %rdx, %r8
+; CHECK-NEXT:    movq %rcx, 16(%rax)
+; CHECK-NEXT:    movq %rsi, (%rax)
+; CHECK-NEXT:    movq %rdi, 24(%rax)
+; CHECK-NEXT:    movq %r8, 8(%rax)
+; CHECK-NEXT:    retq
+  %z = call <2 x i128> @llvm.ssub.sat.v2i128(<2 x i128> %x, <2 x i128> %y)
+  ret <2 x i128> %z
+}
+
+; TODO: Remove the 2nd cmpl by using NF imul.
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KanRobert wrote:

Done @phoebewang 

https://github.com/llvm/llvm-project/pull/93508