[llvm] [GlobalISel] Add GIHasOneUse builtin for combiner match patterns (PR #221804)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,21 @@
+// RUN: llvm-tblgen -I %p/../../../include -gen-global-isel-combiner \
+// RUN:     -combiners=MyCombiner %s | \
+// RUN: FileCheck %s
+
+include "llvm/Target/Target.td"
+include "llvm/Target/GlobalISel/Combine.td"
+
+def MyTargetISA : InstrInfo;
+def MyTarget : Target { let InstructionSet = MyTargetISA; }
+
+// CHECK: GIM_CheckOpcode, /*MI*/1, GIMT_Encode2(TargetOpcode::G_MUL)
+// CHECK: GIM_CheckHasOneUse, /*MI*/1
+def test_has_one_use: GICombineRule<
+  (defs root:$d),
+  (match (G_MUL $mul, $x, $c),
+         (G_SUB $d, $a, $mul),
+         (GIHasOneUse $mul)),
+  (apply (GIReplaceReg $d, $x))
+>;
+
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arsenm wrote:

Do both methods work? If so test both? 

https://github.com/llvm/llvm-project/pull/221804