[llvm] [SelectionDAG] Add preliminary plumbing for `samesign` flag (PR #112354)

[Thorsten Schütt via llvm-commits]

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@@ -0,0 +1,31 @@
+; NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -march=aarch64 -stop-after=finalize-isel -simplify-mir -o - %s | FileCheck %s
+
+define i1 @icmp_samesign(i32 %a, i32 %b) {
+  ; CHECK-LABEL: name: icmp_samesign
+  ; CHECK: bb.0 (%ir-block.0):
+  ; CHECK-NEXT:   liveins: $w0, $w1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[COPY:%[0-9]+]]:gpr32 = COPY $w1
+  ; CHECK-NEXT:   [[COPY1:%[0-9]+]]:gpr32 = COPY $w0
+  ; CHECK-NEXT:   [[SUBSWrr:%[0-9]+]]:gpr32 = SUBSWrr [[COPY1]], [[COPY]], implicit-def $nzcv
+  ; CHECK-NEXT:   [[CSINCWr:%[0-9]+]]:gpr32 = CSINCWr $wzr, $wzr, 2, implicit $nzcv
+  ; CHECK-NEXT:   $w0 = COPY [[CSINCWr]]
+  ; CHECK-NEXT:   RET_ReallyLR implicit $w0
+    %res = icmp samesign ult i32 %a, %b
+    ret i1 %res
+}
+
+define <2 x i1> @icmp_samesign_vec(<2 x i32> %a, <2 x i32> %b) {
+  ; CHECK-LABEL: name: icmp_samesign_vec
+  ; CHECK: bb.0 (%ir-block.0):
+  ; CHECK-NEXT:   liveins: $d0, $d1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[COPY:%[0-9]+]]:fpr64 = COPY $d1
+  ; CHECK-NEXT:   [[COPY1:%[0-9]+]]:fpr64 = COPY $d0
+  ; CHECK-NEXT:   [[CMHIv2i32_:%[0-9]+]]:fpr64 = CMHIv2i32 [[COPY]], [[COPY1]]
+  ; CHECK-NEXT:   $d0 = COPY [[CMHIv2i32_]]
+  ; CHECK-NEXT:   RET_ReallyLR implicit $d0
+  %res = icmp samesign ult <2 x i32> %a, %b
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tschuett wrote:

Could you please add a test without samesign?

https://github.com/llvm/llvm-project/pull/112354