Revert "Strings: Disable precomputing for now (#6412)" (#6413)

This reverts commit 70ac213fce134840609190a5d3a18118a089ba8a.

Reverts #6412

On second thought we found a way to make fixing this less urgent, and the
code size downsides of this are worrying, so let's revert it.

3 files changed, 13 insertions, 74 deletions

diff --git a/src/passes/Precompute.cpp b/src/passes/Precompute.cpp
index 64b555028..d2f3543ad 100644
--- a/src/passes/Precompute.cpp
+++ b/src/passes/Precompute.cpp
@@ -195,36 +195,6 @@ public:
     }
     return Literal(canonical, curr->type.getHeapType());
   }
-
-  // Disable string operations pending investigation of the correctness of our
-  // UTF implementation. FIXME
-  Flow visitStringNew(StringNew* curr) { return Flow(NONCONSTANT_FLOW); }
-  Flow visitStringConst(StringConst* curr) { return Flow(NONCONSTANT_FLOW); }
-  Flow visitStringMeasure(StringMeasure* curr) {
-    return Flow(NONCONSTANT_FLOW);
-  }
-  Flow visitStringConcat(StringConcat* curr) { return Flow(NONCONSTANT_FLOW); }
-  Flow visitStringEncode(StringEncode* curr) { return Flow(NONCONSTANT_FLOW); }
-  Flow visitStringEq(StringEq* curr) { return Flow(NONCONSTANT_FLOW); }
-  Flow visitStringAs(StringAs* curr) { return Flow(NONCONSTANT_FLOW); }
-  Flow visitStringWTF8Advance(StringWTF8Advance* curr) {
-    return Flow(NONCONSTANT_FLOW);
-  }
-  Flow visitStringWTF16Get(StringWTF16Get* curr) {
-    return Flow(NONCONSTANT_FLOW);
-  }
-  Flow visitStringIterNext(StringIterNext* curr) {
-    return Flow(NONCONSTANT_FLOW);
-  }
-  Flow visitStringIterMove(StringIterMove* curr) {
-    return Flow(NONCONSTANT_FLOW);
-  }
-  Flow visitStringSliceWTF(StringSliceWTF* curr) {
-    return Flow(NONCONSTANT_FLOW);
-  }
-  Flow visitStringSliceIter(StringSliceIter* curr) {
-    return Flow(NONCONSTANT_FLOW);
-  }
 };
 
 struct Precompute
diff --git a/test/lit/passes/precompute-gc.wast b/test/lit/passes/precompute-gc.wast
index 204467f51..2b16cb43f 100644
--- a/test/lit/passes/precompute-gc.wast
+++ b/test/lit/passes/precompute-gc.wast
@@ -1019,10 +1019,10 @@
  ;; CHECK-NEXT:   (string.const "hello, world")
  ;; CHECK-NEXT:  )
  ;; CHECK-NEXT:  (call $strings
- ;; CHECK-NEXT:   (local.get $s)
+ ;; CHECK-NEXT:   (string.const "hello, world")
  ;; CHECK-NEXT:  )
  ;; CHECK-NEXT:  (call $strings
- ;; CHECK-NEXT:   (local.get $s)
+ ;; CHECK-NEXT:   (string.const "hello, world")
  ;; CHECK-NEXT:  )
  ;; CHECK-NEXT: )
  (func $strings (param $param (ref string))
diff --git a/test/lit/passes/precompute-strings.wast b/test/lit/passes/precompute-strings.wast
index 4cd6a8237..c9facfe36 100644
--- a/test/lit/passes/precompute-strings.wast
+++ b/test/lit/passes/precompute-strings.wast
@@ -5,11 +5,11 @@
 (module
  ;; CHECK:      (type $0 (func (result i32)))
 
+ ;; CHECK:      (type $1 (func (result (ref string))))
+
  ;; CHECK:      (type $array16 (array (mut i16)))
  (type $array16 (array (mut i16)))
 
- ;; CHECK:      (type $2 (func (result (ref string))))
-
  ;; CHECK:      (export "get_codepoint-bad" (func $get_codepoint-bad))
 
  ;; CHECK:      (export "slice" (func $slice))
@@ -17,10 +17,7 @@
  ;; CHECK:      (export "slice-bad" (func $slice-bad))
 
  ;; CHECK:      (func $eq-no (type $0) (result i32)
- ;; CHECK-NEXT:  (string.eq
- ;; CHECK-NEXT:   (string.const "ab")
- ;; CHECK-NEXT:   (string.const "cdefg")
- ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (i32.const 0)
  ;; CHECK-NEXT: )
  (func $eq-no (result i32)
   (string.eq
@@ -30,10 +27,7 @@
  )
 
  ;; CHECK:      (func $eq-yes (type $0) (result i32)
- ;; CHECK-NEXT:  (string.eq
- ;; CHECK-NEXT:   (string.const "ab")
- ;; CHECK-NEXT:   (string.const "ab")
- ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (i32.const 1)
  ;; CHECK-NEXT: )
  (func $eq-yes (result i32)
   (string.eq
@@ -43,13 +37,7 @@
  )
 
  ;; CHECK:      (func $concat (type $0) (result i32)
- ;; CHECK-NEXT:  (string.eq
- ;; CHECK-NEXT:   (string.concat
- ;; CHECK-NEXT:    (string.const "a")
- ;; CHECK-NEXT:    (string.const "b")
- ;; CHECK-NEXT:   )
- ;; CHECK-NEXT:   (string.const "ab")
- ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (i32.const 1)
  ;; CHECK-NEXT: )
  (func $concat (result i32)
   (string.eq
@@ -75,11 +63,7 @@
  )
 
  ;; CHECK:      (func $length (type $0) (result i32)
- ;; CHECK-NEXT:  (stringview_wtf16.length
- ;; CHECK-NEXT:   (string.as_wtf16
- ;; CHECK-NEXT:    (string.const "1234567")
- ;; CHECK-NEXT:   )
- ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (i32.const 7)
  ;; CHECK-NEXT: )
  (func $length (result i32)
   (stringview_wtf16.length
@@ -107,12 +91,7 @@
  )
 
  ;; CHECK:      (func $get_codepoint (type $0) (result i32)
- ;; CHECK-NEXT:  (stringview_wtf16.get_codeunit
- ;; CHECK-NEXT:   (string.as_wtf16
- ;; CHECK-NEXT:    (string.const "$_\c2\a3_\e2\82\ac_\f0\90\8d\88")
- ;; CHECK-NEXT:   )
- ;; CHECK-NEXT:   (i32.const 1)
- ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (i32.const 95)
  ;; CHECK-NEXT: )
  (func $get_codepoint (result i32)
   ;; This is computable because everything up to the requested index is ascii. Returns 95 ('_').
@@ -145,13 +124,7 @@
  )
 
  ;; CHECK:      (func $encode (type $0) (result i32)
- ;; CHECK-NEXT:  (string.encode_wtf16_array
- ;; CHECK-NEXT:   (string.const "$_")
- ;; CHECK-NEXT:   (array.new_default $array16
- ;; CHECK-NEXT:    (i32.const 20)
- ;; CHECK-NEXT:   )
- ;; CHECK-NEXT:   (i32.const 0)
- ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  (i32.const 2)
  ;; CHECK-NEXT: )
  (func $encode (result i32)
   (string.encode_wtf16_array
@@ -183,12 +156,8 @@
   )
  )
 
- ;; CHECK:      (func $slice (type $2) (result (ref string))
- ;; CHECK-NEXT:  (stringview_wtf16.slice
- ;; CHECK-NEXT:   (string.const "abcdefgh")
- ;; CHECK-NEXT:   (i32.const 3)
- ;; CHECK-NEXT:   (i32.const 6)
- ;; CHECK-NEXT:  )
+ ;; CHECK:      (func $slice (type $1) (result (ref string))
+ ;; CHECK-NEXT:  (string.const "def")
  ;; CHECK-NEXT: )
  (func $slice (export "slice") (result (ref string))
   ;; Slicing [3:6] here should definitely output "def".
@@ -199,7 +168,7 @@
   )
  )
 
- ;; CHECK:      (func $slice-bad (type $2) (result (ref string))
+ ;; CHECK:      (func $slice-bad (type $1) (result (ref string))
  ;; CHECK-NEXT:  (stringview_wtf16.slice
  ;; CHECK-NEXT:   (string.const "abcd\c2\a3fgh")
  ;; CHECK-NEXT:   (i32.const 3)