From 2af7ab3b168e5239b65858251da93670357a8312 Mon Sep 17 00:00:00 2001
From: Alastair Donaldson <afdx@google.com>
Date: Thu, 29 Sep 2022 14:36:08 +0000
Subject: [PATCH] Add missing operator to regex fuzzer

Fixes a problem where the regex fuzzer would identify '==' as a
candidate operator for replacement, but where the replacement code did
not actually handle the '==' case.

Fixes http://crbug.com/1367902
Change-Id: I9a3bda9e7bae5e42872f17427419ab690d477533

Change-Id: If9cbb2db779c6873ff7a02d132981e8ee3410bb1
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/104200
Commit-Queue: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Auto-Submit: Alastair Donaldson <afdx@google.com>
---
 .../fuzzers/tint_regex_fuzzer/wgsl_mutator.cc | 25 ++++++++-----------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/src/tint/fuzzers/tint_regex_fuzzer/wgsl_mutator.cc b/src/tint/fuzzers/tint_regex_fuzzer/wgsl_mutator.cc
index c5125a4143..7d16aadc72 100644
--- a/src/tint/fuzzers/tint_regex_fuzzer/wgsl_mutator.cc
+++ b/src/tint/fuzzers/tint_regex_fuzzer/wgsl_mutator.cc
@@ -416,7 +416,7 @@ std::string WgslMutator::ChooseRandomReplacementForOperator(const std::string& e
         "=", "+=", "-=", "*=", "/=", "%=", "&=", "|=", "^=", "<<=", ">>="};
     std::vector<std::string> expression_operators{"+",  "-",  "*", "/",  "%",  "&&", "||",
                                                   "&",  "|",  "^", "<<", ">>", "<",  ">",
-                                                  "<=", ">=", "!", "!=", "~"};
+                                                  "<=", ">=", "!", "==", "!=", "~"};
     std::vector<std::string> increment_operators{"++", "--"};
     for (auto operators : {assignment_operators, expression_operators, increment_operators}) {
         auto it = std::find(operators.begin(), operators.end(), existing_operator);
@@ -471,6 +471,12 @@ std::optional<std::pair<uint32_t, uint32_t>> WgslMutator::FindOperatorOccurrence
         switch (first_character) {
             case '!':
             case '^':
+            case '*':
+            case '/':
+            case '%':
+            case '=':
+                // The above cases are all stand-alone operators, and if followed by '=' are also
+                // operators.
                 switch (second_character) {
                     case '=':
                         return {{current_index, 2}};
@@ -481,26 +487,15 @@ std::optional<std::pair<uint32_t, uint32_t>> WgslMutator::FindOperatorOccurrence
             case '&':
             case '+':
             case '-':
+                // The above cases are all stand-alone operators, and if repeated or followed by '='
+                // are also operators.
                 if (second_character == first_character || second_character == '=') {
                     return {{current_index, 2}};
                 }
                 return {{current_index, 1}};
-            case '*':
-            case '/':
-            case '%':
-                switch (second_character) {
-                    case '=':
-                        return {{current_index, 2}};
-                    default:
-                        return {{current_index, 1}};
-                }
-            case '=':
-                if (second_character == '=') {
-                    return {{current_index, 2}};
-                }
-                return {{current_index, 1}};
             case '<':
             case '>':
+                // The following caters for '<', '<=', '<<', '<<=', '>', '>=', '>>' and '>>='.
                 if (second_character == '=') {
                     return {{current_index, 2}};
                 }