[NFC] DeNaN: Avoid calls on constants (#6326)

A constant is either fixed up immediately, or does not need a call. This makes us
slightly faster in the fuzzer, but does not change behavior as before those calls all
ended up doing nothing (as the numbers were not nans).

3 files changed, 40 insertions, 7 deletions

diff --git a/src/passes/DeNaN.cpp b/src/passes/DeNaN.cpp
index b0bd5fb60..0251a0c58 100644
--- a/src/passes/DeNaN.cpp
+++ b/src/passes/DeNaN.cpp
@@ -58,20 +58,20 @@ struct DeNaN : public WalkerPass<
     if (expr->type == Type::f32) {
       if (c && c->value.isNaN()) {
         replacement = builder.makeConst(float(0));
-      } else {
+      } else if (!c) {
         replacement = builder.makeCall(deNan32, {expr}, Type::f32);
       }
     } else if (expr->type == Type::f64) {
       if (c && c->value.isNaN()) {
         replacement = builder.makeConst(double(0));
-      } else {
+      } else if (!c) {
         replacement = builder.makeCall(deNan64, {expr}, Type::f64);
       }
     } else if (expr->type == Type::v128) {
       if (c && hasNaNLane(c)) {
         uint8_t zero[16] = {};
         replacement = builder.makeConst(Literal(zero));
-      } else {
+      } else if (!c) {
         replacement = builder.makeCall(deNan128, {expr}, Type::v128);
       }
     }
diff --git a/test/lit/passes/denan-simd.wast b/test/lit/passes/denan-simd.wast
index 3ab4e9120..6508b36eb 100644
--- a/test/lit/passes/denan-simd.wast
+++ b/test/lit/passes/denan-simd.wast
@@ -16,9 +16,7 @@
   ;; CHECK-NEXT:   )
   ;; CHECK-NEXT:  )
   ;; CHECK-NEXT:  (drop
-  ;; CHECK-NEXT:   (call $deNan128
-  ;; CHECK-NEXT:    (v128.const i32x4 0x00000001 0x00000002 0x00000003 0x00000004)
-  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:   (v128.const i32x4 0x00000001 0x00000002 0x00000003 0x00000004)
   ;; CHECK-NEXT:  )
   ;; CHECK-NEXT:  (drop
   ;; CHECK-NEXT:   (v128.const i32x4 0x00000000 0x00000000 0x00000000 0x00000000)
@@ -35,7 +33,7 @@
   (func $foo128 (param $x v128) (result v128)
     ;; The incoming param will be de-naned.
 
-    ;; This is not a NaN. (We do still emit a call for it atm, FIXME)
+    ;; This is not a NaN.
     (drop
       (v128.const i32x4 0x00000001 0x00000002 0x00000003 0x00000004)
     )
@@ -48,6 +46,7 @@
       (v128.const i32x4 0x00000001 0xffffffff 0x00000003 0x00000004)
     )
 
+    ;; The result here will be de-naned.
     (call $foo128 (local.get $x))
   )
 )
diff --git a/test/lit/passes/denan.wast b/test/lit/passes/denan.wast
index 7baabc369..bc42ab04e 100644
--- a/test/lit/passes/denan.wast
+++ b/test/lit/passes/denan.wast
@@ -12,6 +12,8 @@
 
   ;; CHECK:      (type $3 (func (param f32 f64)))
 
+  ;; CHECK:      (type $4 (func))
+
   ;; CHECK:      (global $global$1 (mut f32) (f32.const 0))
   (global $global$1 (mut f32) (f32.const nan))
   ;; CHECK:      (global $global$2 (mut f32) (f32.const 12.34000015258789))
@@ -139,6 +141,38 @@
     (drop (local.get $f))
     (drop (local.get $d))
   )
+
+  ;; CHECK:      (func $constants
+  ;; CHECK-NEXT:  (drop
+  ;; CHECK-NEXT:   (f32.const 12.34000015258789)
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT:  (drop
+  ;; CHECK-NEXT:   (f32.const 0)
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT:  (drop
+  ;; CHECK-NEXT:   (f64.const 12.34)
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT:  (drop
+  ;; CHECK-NEXT:   (f64.const 0)
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $constants
+    ;; Constants can be fixed up or left alone - we never need to add a call on
+    ;; them.
+    (drop
+      (f32.const 12.34)
+    )
+    (drop
+      (f32.const nan)
+    )
+    (drop
+      (f64.const 12.34)
+    )
+    (drop
+      (f64.const nan)
+    )
+  )
+
   ;; CHECK:      (func $tees (param $x f32) (result f32)
   ;; CHECK-NEXT:  (local.set $x
   ;; CHECK-NEXT:   (call $deNan32