[liftoff][arm] Handle trivial case for FloatMax.

Move lhs into dst when lhs == rhs.

Bug: v8:6600, chromium:910223
Change-Id: I5bcb01b57705c52f363a43b2036f0ade0fd451e7
Reviewed-on: https://chromium-review.googlesource.com/c/1357041
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57996}

src/wasm/baseline/arm/liftoff-assembler-arm.h

@@ -175,6 +175,10 @@ inline void EmitFloatMinOrMax(LiftoffAssembler* assm, RegisterType dst,
                               RegisterType lhs, RegisterType rhs,
                               MinOrMax min_or_max) {
   DCHECK(RegisterType::kSizeInBytes == 4 || RegisterType::kSizeInBytes == 8);
+  if (lhs == rhs) {
+    assm->TurboAssembler::Move(dst, lhs);
+    return;
+  }
   Label done, is_nan;
   if (min_or_max == MinOrMax::kMin) {
     assm->TurboAssembler::FloatMin(dst, lhs, rhs, &is_nan);

test/cctest/wasm/test-run-wasm.cc

@@ -2839,6 +2839,13 @@ WASM_EXEC_TEST(F32Min) {
   }
 }
 
+WASM_EXEC_TEST(F32MinSameValue) {
+  WasmRunner<float, float> r(execution_tier);
+  BUILD(r, WASM_F32_MIN(WASM_GET_LOCAL(0), WASM_GET_LOCAL(0)));
+  float result = r.Call(5.0f);
+  CHECK_FLOAT_EQ(5.0f, result);
+}
+
 WASM_EXEC_TEST(F64Min) {
   WasmRunner<double, double, double> r(execution_tier);
   BUILD(r, WASM_F64_MIN(WASM_GET_LOCAL(0), WASM_GET_LOCAL(1)));
@@ -2848,6 +2855,13 @@ WASM_EXEC_TEST(F64Min) {
   }
 }
 
+WASM_EXEC_TEST(F64MinSameValue) {
+  WasmRunner<double, double> r(execution_tier);
+  BUILD(r, WASM_F64_MIN(WASM_GET_LOCAL(0), WASM_GET_LOCAL(0)));
+  double result = r.Call(5.0);
+  CHECK_DOUBLE_EQ(5.0, result);
+}
+
 WASM_EXEC_TEST(F32Max) {
   WasmRunner<float, float, float> r(execution_tier);
   BUILD(r, WASM_F32_MAX(WASM_GET_LOCAL(0), WASM_GET_LOCAL(1)));
@@ -2857,6 +2871,13 @@ WASM_EXEC_TEST(F32Max) {
   }
 }
 
+WASM_EXEC_TEST(F32MaxSameValue) {
+  WasmRunner<float, float> r(execution_tier);
+  BUILD(r, WASM_F32_MAX(WASM_GET_LOCAL(0), WASM_GET_LOCAL(0)));
+  float result = r.Call(5.0f);
+  CHECK_FLOAT_EQ(5.0f, result);
+}
+
 WASM_EXEC_TEST(F64Max) {
   WasmRunner<double, double, double> r(execution_tier);
   BUILD(r, WASM_F64_MAX(WASM_GET_LOCAL(0), WASM_GET_LOCAL(1)));
@@ -2869,6 +2890,13 @@ WASM_EXEC_TEST(F64Max) {
   }
 }
 
+WASM_EXEC_TEST(F64MaxSameValue) {
+  WasmRunner<double, double> r(execution_tier);
+  BUILD(r, WASM_F64_MAX(WASM_GET_LOCAL(0), WASM_GET_LOCAL(0)));
+  double result = r.Call(5.0);
+  CHECK_DOUBLE_EQ(5.0, result);
+}
+
 WASM_EXEC_TEST(I32SConvertF32) {
   WasmRunner<int32_t, float> r(execution_tier);
   BUILD(r, WASM_I32_SCONVERT_F32(WASM_GET_LOCAL(0)));