From 7c80806afb98d177b5160431a4235484341b0ed5 Mon Sep 17 00:00:00 2001
From: Thomas Lively <tlively@google.com>
Date: Fri, 27 Feb 2026 23:45:22 -0800
Subject: [PATCH] Validate SIMDTernary features

Require relaxed SIMD and fp16 features for those instructions that need
them. This will prevent the fuzzer (and the clusterfuzz fuzzer in
particular) from picking up initial content that uses fp16 operations,
which it does not yet support.
---
 src/wasm/wasm-validator.cpp           | 29 ++++++++++++++++++++++++---
 test/lit/validation/simd-ternary.wast | 10 +++++++++
 2 files changed, 36 insertions(+), 3 deletions(-)
 create mode 100644 test/lit/validation/simd-ternary.wast

diff --git a/src/wasm/wasm-validator.cpp b/src/wasm/wasm-validator.cpp
index ca550d7225a..0a6d205ee63 100644
--- a/src/wasm/wasm-validator.cpp
+++ b/src/wasm/wasm-validator.cpp
@@ -31,6 +31,7 @@
 #include "ir/stack-utils.h"
 #include "ir/utils.h"
 #include "support/colors.h"
+#include "wasm-features.h"
 #include "wasm-type.h"
 #include "wasm-validator.h"
 #include "wasm.h"
@@ -1500,9 +1501,31 @@ void FunctionValidator::visitSIMDShuffle(SIMDShuffle* curr) {
 }
 
 void FunctionValidator::visitSIMDTernary(SIMDTernary* curr) {
-  shouldBeTrue(getModule()->features.hasSIMD(),
-               curr,
-               "SIMD operations require SIMD [--enable-simd]");
+  FeatureSet required = FeatureSet::None;
+  switch (curr->op) {
+    case RelaxedMaddVecF16x8:
+    case RelaxedNmaddVecF16x8:
+      required |= FeatureSet::FP16;
+      [[fallthrough]];
+    case LaneselectI8x16:
+    case LaneselectI16x8:
+    case LaneselectI32x4:
+    case LaneselectI64x2:
+    case RelaxedMaddVecF32x4:
+    case RelaxedNmaddVecF32x4:
+    case RelaxedMaddVecF64x2:
+    case RelaxedNmaddVecF64x2:
+    case DotI8x16I7x16AddSToVecI32x4:
+      required |= FeatureSet::RelaxedSIMD;
+      [[fallthrough]];
+    case Bitselect:
+      required |= FeatureSet::SIMD;
+  }
+  if (!shouldBeTrue(required <= getModule()->features,
+                    curr,
+                    "SIMD ternary operation requires additional features")) {
+    getStream() << getMissingFeaturesList(*getModule(), required) << '\n';
+  }
   shouldBeEqualOrFirstIsUnreachable(
     curr->type, Type(Type::v128), curr, "SIMD ternary must have type v128");
   shouldBeEqualOrFirstIsUnreachable(
diff --git a/test/lit/validation/simd-ternary.wast b/test/lit/validation/simd-ternary.wast
new file mode 100644
index 00000000000..31e3abced20
--- /dev/null
+++ b/test/lit/validation/simd-ternary.wast
@@ -0,0 +1,10 @@
+;; RUN: not wasm-opt --enable-simd %s 2>&1 | filecheck %s
+
+;; CHECK: SIMD ternary operation requires additional features, on
+;; CHECK: [--enable-relaxed-simd --enable-fp16]
+
+(module
+  (func $fp16 (param v128 v128 v128)
+    (f16x8.relaxed_madd (local.get 0) (local.get 1) (local.get 2))
+  )
+)