1 files changed, 61 insertions, 0 deletions
diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp
index 8b71da824..b50f99fbc 100644
--- a/src/passes/OptimizeInstructions.cpp
+++ b/src/passes/OptimizeInstructions.cpp
@@ -2157,6 +2157,67 @@ private:
         c->value = Literal::makeZero(c->type);
         return;
       }
+      // Prefer compare to signed min (s_min) instead of s_min + 1.
+      // (signed)x < s_min + 1   ==>   x == s_min
+      if (binary->op == LtSInt32 && c->value.geti32() == INT32_MIN + 1) {
+        binary->op = EqInt32;
+        c->value = Literal::makeSignedMin(Type::i32);
+        return;
+      }
+      if (binary->op == LtSInt64 && c->value.geti64() == INT64_MIN + 1) {
+        binary->op = EqInt64;
+        c->value = Literal::makeSignedMin(Type::i64);
+        return;
+      }
+      // (signed)x >= s_min + 1   ==>   x != s_min
+      if (binary->op == GeSInt32 && c->value.geti32() == INT32_MIN + 1) {
+        binary->op = NeInt32;
+        c->value = Literal::makeSignedMin(Type::i32);
+        return;
+      }
+      if (binary->op == GeSInt64 && c->value.geti64() == INT64_MIN + 1) {
+        binary->op = NeInt64;
+        c->value = Literal::makeSignedMin(Type::i64);
+        return;
+      }
+      // Prefer compare to signed max (s_max) instead of s_max - 1.
+      // (signed)x > s_max - 1   ==>   x == s_max
+      if (binary->op == GtSInt32 && c->value.geti32() == INT32_MAX - 1) {
+        binary->op = EqInt32;
+        c->value = Literal::makeSignedMax(Type::i32);
+        return;
+      }
+      if (binary->op == GtSInt64 && c->value.geti64() == INT64_MAX - 1) {
+        binary->op = EqInt64;
+        c->value = Literal::makeSignedMax(Type::i64);
+        return;
+      }
+      // (signed)x <= s_max - 1   ==>   x != s_max
+      if (binary->op == LeSInt32 && c->value.geti32() == INT32_MAX - 1) {
+        binary->op = NeInt32;
+        c->value = Literal::makeSignedMax(Type::i32);
+        return;
+      }
+      if (binary->op == LeSInt64 && c->value.geti64() == INT64_MAX - 1) {
+        binary->op = NeInt64;
+        c->value = Literal::makeSignedMax(Type::i64);
+        return;
+      }
+      // Prefer compare to unsigned max (u_max) instead of u_max - 1.
+      // (unsigned)x <= u_max - 1   ==>   x != u_max
+      if (binary->op == Abstract::getBinary(c->type, Abstract::LeU) &&
+          c->value.getInteger() == (int64_t)(UINT64_MAX - 1)) {
+        binary->op = Abstract::getBinary(c->type, Abstract::Ne);
+        c->value = Literal::makeUnsignedMax(c->type);
+        return;
+      }
+      // (unsigned)x > u_max - 1   ==>   x == u_max
+      if (binary->op == Abstract::getBinary(c->type, Abstract::GtU) &&
+          c->value.getInteger() == (int64_t)(UINT64_MAX - 1)) {
+        binary->op = Abstract::getBinary(c->type, Abstract::Eq);
+        c->value = Literal::makeUnsignedMax(c->type);
+        return;
+      }
       return;
     }
     // Prefer a get on the right.