Revert "Partially fix Precompute on SIMD (#3983)" (#4002)

This reverts commit b68691e826a46d1b03b27c552b1f5b7f51f92665.

Instead of applying the workaround to avoid precomputing SIMD in more places,
which prevents things we could optimize before, we should probably focus on
making the workaround not needed - that is, implement full SIMD support in the
intepreter (the reason for that PR), and the other TODO in the comment here,

    // Until engines implement v128.const and we have SIMD-aware optimizations
    // that can break large v128.const instructions into smaller consts and
    // splats, do not try to precompute v128 expressions.

3 files changed, 10 insertions, 24 deletions

diff --git a/src/passes/Precompute.cpp b/src/passes/Precompute.cpp
index fa6e8e9ed..a832c9e85 100644
--- a/src/passes/Precompute.cpp
+++ b/src/passes/Precompute.cpp
@@ -172,8 +172,17 @@ struct Precompute
     if (Properties::isConstantExpression(curr) || curr->is<Nop>()) {
       return;
     }
+    // Until engines implement v128.const and we have SIMD-aware optimizations
+    // that can break large v128.const instructions into smaller consts and
+    // splats, do not try to precompute v128 expressions.
+    if (curr->type.isVector()) {
+      return;
+    }
     // try to evaluate this into a const
     Flow flow = precomputeExpression(curr);
+    if (flow.getType().hasVector()) {
+      return;
+    }
     if (!canEmitConstantFor(flow.values)) {
       return;
     }
@@ -227,12 +236,6 @@ private:
   // Precompute an expression, returning a flow, which may be a constant
   // (that we can replace the expression with if replaceExpression is set).
   Flow precomputeExpression(Expression* curr, bool replaceExpression = true) {
-    // Until engines implement v128.const and we have SIMD-aware optimizations
-    // that can break large v128.const instructions into smaller consts and
-    // splats, do not try to precompute v128 expressions.
-    if (curr->type.isVector()) {
-      return Flow(NONCONSTANT_FLOW);
-    }
     Flow flow;
     try {
       flow =
@@ -247,9 +250,6 @@ private:
         !canEmitConstantFor(flow.values)) {
       return Flow(NONCONSTANT_FLOW);
     }
-    if (flow.getType().hasVector()) {
-      return Flow(NONCONSTANT_FLOW);
-    }
     return flow;
   }
 
diff --git a/test/passes/precompute_all-features.txt b/test/passes/precompute_all-features.txt
index dc93f90e4..b707f4248 100644
--- a/test/passes/precompute_all-features.txt
+++ b/test/passes/precompute_all-features.txt
@@ -1,8 +1,8 @@
 (module
  (type $none_=>_none (func))
  (type $none_=>_i32 (func (result i32)))
- (type $none_=>_v128 (func (result v128)))
  (type $none_=>_f64 (func (result f64)))
+ (type $none_=>_v128 (func (result v128)))
  (type $0 (func (param i32)))
  (type $none_=>_i32_i64 (func (result i32 i64)))
  (type $none_=>_externref (func (result externref)))
@@ -222,13 +222,6 @@
    (i32.const 0)
   )
  )
- (func $no-simd-precompute_2 (result v128)
-  (i32x4.extadd_pairwise_i16x8_s
-   (i32x4.splat
-    (i32.const 0)
-   )
-  )
- )
  (func $no-simd-precompute-if (result v128)
   (return
    (i32x4.splat
diff --git a/test/passes/precompute_all-features.wast b/test/passes/precompute_all-features.wast
index e306be495..1275524e0 100644
--- a/test/passes/precompute_all-features.wast
+++ b/test/passes/precompute_all-features.wast
@@ -329,13 +329,6 @@
     (i32.const 0)
    )
   )
-  (func $no-simd-precompute_2 (result v128)
-   (i32x4.extadd_pairwise_i16x8_s
-    (i32x4.splat
-     (i32.const 0)
-    )
-   )
-  )
   (func $no-simd-precompute-if (result v128)
    (return
     (i32x4.splat