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-rw-r--r--src/cmd/compile/internal/ssa/_gen/generic.rules9
1 files changed, 9 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ssa/_gen/generic.rules b/src/cmd/compile/internal/ssa/_gen/generic.rules
index 4c475d31e00..398601e81b4 100644
--- a/src/cmd/compile/internal/ssa/_gen/generic.rules
+++ b/src/cmd/compile/internal/ssa/_gen/generic.rules
@@ -2794,3 +2794,12 @@
(Load <t> (OffPtr [off] (Convert (Addr {sym} _) _) ) _) && t.IsInteger() && t.Size() == 4 && isFixed32(config, sym, off) => (Const32 [fixed32(config, sym, off)])
(Load <t> (OffPtr [off] (ITab (IMake (Addr {sym} _) _))) _) && t.IsInteger() && t.Size() == 4 && isFixed32(config, sym, off) => (Const32 [fixed32(config, sym, off)])
(Load <t> (OffPtr [off] (ITab (IMake (Convert (Addr {sym} _) _) _))) _) && t.IsInteger() && t.Size() == 4 && isFixed32(config, sym, off) => (Const32 [fixed32(config, sym, off)])
+
+// Calling cmpstring a second time with the same arguments in the
+// same memory state can reuse the results of the first call.
+// See issue 61725.
+// Note that this could pretty easily generalize to any pure function.
+(StaticLECall {f} x y m:(SelectN [1] c:(StaticLECall {g} x y mem)))
+ && isSameCall(f, "runtime.cmpstring")
+ && isSameCall(g, "runtime.cmpstring")
+=> (MakeResult (SelectN [0] <typ.Int> c) m)