[llvm] [GlobalISel] Combine [S,U]SUBO (PR #116489)

[Matt Arsenault via llvm-commits]

================
@@ -176,3 +176,49 @@ body:             |
     $q1 = COPY %o_wide
     RET_ReallyLR implicit $w0
 ...
+---
+name:            sub_may
+body:             |
+  bb.0:
+    liveins: $w0, $w1
+    ; CHECK-LABEL: name: sub_may
+    ; CHECK: liveins: $w0, $w1
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $w0
+    ; CHECK-NEXT: %const:_(s32) = G_CONSTANT i32 512
+    ; CHECK-NEXT: %sub:_(s32), %o:_(s1) = G_SSUBO [[COPY]], %const
+    ; CHECK-NEXT: %o_wide:_(s32) = G_ZEXT %o(s1)
+    ; CHECK-NEXT: $w0 = COPY %sub(s32)
+    ; CHECK-NEXT: $w1 = COPY %o_wide(s32)
+    ; CHECK-NEXT: RET_ReallyLR implicit $w0
+    %0:_(s32) = COPY $w0
+    %const:_(s32) = G_CONSTANT i32 512
+    %sub:_(s32), %o:_(s1) = G_SSUBO %0, %const
+    %o_wide:_(s32) = G_ZEXT %o(s1)
+    $w0 = COPY %sub(s32)
+    $w1 = COPY %o_wide
+    RET_ReallyLR implicit $w0
+...
+---
+name:            usub_may
+body:             |
+  bb.0:
+    liveins: $w0, $w1
+    ; CHECK-LABEL: name: usub_may
+    ; CHECK: liveins: $w0, $w1
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $w0
+    ; CHECK-NEXT: %const:_(s32) = G_CONSTANT i32 512
+    ; CHECK-NEXT: %sub:_(s32), %o:_(s1) = G_USUBO [[COPY]], %const
+    ; CHECK-NEXT: %o_wide:_(s32) = G_ZEXT %o(s1)
+    ; CHECK-NEXT: $w0 = COPY %sub(s32)
+    ; CHECK-NEXT: $w1 = COPY %o_wide(s32)
+    ; CHECK-NEXT: RET_ReallyLR implicit $w0
+    %0:_(s32) = COPY $w0
+    %const:_(s32) = G_CONSTANT i32 512
+    %sub:_(s32), %o:_(s1) = G_USUBO %0, %const
+    %o_wide:_(s32) = G_ZEXT %o(s1)
+    $w0 = COPY %sub(s32)
+    $w1 = COPY %o_wide
+    RET_ReallyLR implicit $w0
+...
----------------
arsenm wrote:

Add a test with a non-s1 carry output, and vectors 

https://github.com/llvm/llvm-project/pull/116489