[PATCH 3/3] remove early simplification of casts during evaluation

[Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>]

The current code will simplify away some casts at evaluation time
but doesn't take in account some special cases:
* (bool)~<int>  is not equivalent to ~(bool)<int> (anything not all 0 or 1)
* (float)~<int> is not equivalent to ~(float)<int> which doesn't make sense.
* (int)(float)<int> is not a no-op if the (float) overflows

This kind of simplification is better done on the IR where the different
kind of casts correspond to distinct instructions.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
 evaluate.c                       | 44 +-------------------------------
 validation/eval/not-cast-bool.c  |  1 -
 validation/eval/not-cast-float.c |  1 -
 3 files changed, 1 insertion(+), 45 deletions(-)

diff --git a/evaluate.c b/evaluate.c
index eea6b7adcf64..61f59ee3908e 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -226,12 +226,6 @@ static struct symbol *bigger_int_type(struct symbol *left, struct symbol *right)
 	return utype;
 }
 
-static int same_cast_type(struct symbol *orig, struct symbol *new)
-{
-	return orig->bit_size == new->bit_size &&
-	       orig->bit_offset == new->bit_offset;
-}
-
 static struct symbol *base_type(struct symbol *node, unsigned long *modp, struct ident **asp)
 {
 	unsigned long mod = 0;
@@ -316,10 +310,7 @@ static struct symbol *cast_to_bool(struct expression *expr);
 
 /*
  * This gets called for implicit casts in assignments and
- * integer promotion. We often want to try to move the
- * cast down, because the ops involved may have been
- * implicitly cast up, and we can get rid of the casts
- * early.
+ * integer promotion.
  */
 static struct expression * cast_to(struct expression *old, struct symbol *type)
 {
@@ -330,39 +321,6 @@ static struct expression * cast_to(struct expression *old, struct symbol *type)
 	if (old->ctype != &null_ctype && is_same_type(old, type))
 		return old;
 
-	/*
-	 * See if we can simplify the op. Move the cast down.
-	 */
-	switch (old->type) {
-	case EXPR_PREOP:
-		if (old->ctype->bit_size < type->bit_size)
-			break;
-		if (old->op == '~') {
-			old->ctype = type;
-			old->unop = cast_to(old->unop, type);
-			return old;
-		}
-		break;
-
-	case EXPR_IMPLIED_CAST:
-		warn_for_different_enum_types(old->pos, old->ctype, type);
-
-		if (old->ctype->bit_size >= type->bit_size) {
-			struct expression *orig = old->cast_expression;
-			if (same_cast_type(orig->ctype, type))
-				return orig;
-			if (old->ctype->bit_offset == type->bit_offset) {
-				old->ctype = type;
-				old->cast_type = type;
-				return old;
-			}
-		}
-		break;
-
-	default:
-		/* nothing */;
-	}
-
 	expr = alloc_expression(old->pos, EXPR_IMPLIED_CAST);
 	expr->ctype = type;
 	expr->cast_type = type;
diff --git a/validation/eval/not-cast-bool.c b/validation/eval/not-cast-bool.c
index af4224125c34..acd8bbf293db 100644
--- a/validation/eval/not-cast-bool.c
+++ b/validation/eval/not-cast-bool.c
@@ -8,7 +8,6 @@ static _Bool foo(void)
 /*
  * check-name: not-cast-bool
  * check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
  *
  * check-output-ignore
  * check-output-returns: 1
diff --git a/validation/eval/not-cast-float.c b/validation/eval/not-cast-float.c
index 445b91d7563e..d474d69bdda3 100644
--- a/validation/eval/not-cast-float.c
+++ b/validation/eval/not-cast-float.c
@@ -8,7 +8,6 @@ static int foo(void)
 /*
  * check-name: eval-bool-zext-neg
  * check-command: test-linearize -Wno-decl $file
- * check-known-to-fail
  *
  * check-output-ignore
  * check-output-returns: 1
-- 
2.31.1