Hi!
On Fri, Sep 30, 2011 at 10:34:28AM +0200, Richard Guenther wrote:
> Hmm, I don't think this change is ok. We rely on maybe_fold_reference
> to re-fold mem-refs to valid gimple form (from propagating say
> &a.b.c to MEM[p, 4] which first gives the invalid MEM[&a.b.c, 4] and
> then the folding changes this to MEM[&a, 12]). You need to preserve that
> and only disable constant folding.
>
> Thus I suggest to add a parameter to maybe_fold_reference that says
> whether to try constant folding (we already have is_lhs, so why not
> use that?)
So like this instead?
2011-09-30 Jakub Jelinek <ja...@redhat.com>
PR inline-asm/50571
* gimple-fold.c (fold_stmt_1) <case GIMPLE_ASM>: If
input constraints allow mem and not reg, pass true instead of
false as second argument to maybe_fold_reference.
* gcc.dg/pr50571.c: New test.
--- gcc/gimple-fold.c.jj 2011-09-29 14:25:46.000000000 +0200
+++ gcc/gimple-fold.c 2011-09-30 10:54:10.000000000 +0200
@@ -1201,28 +1201,45 @@ fold_stmt_1 (gimple_stmt_iterator *gsi,
case GIMPLE_ASM:
/* Fold *& in asm operands. */
- for (i = 0; i < gimple_asm_noutputs (stmt); ++i)
- {
- tree link = gimple_asm_output_op (stmt, i);
- tree op = TREE_VALUE (link);
- if (REFERENCE_CLASS_P (op)
- && (op = maybe_fold_reference (op, true)) != NULL_TREE)
- {
- TREE_VALUE (link) = op;
- changed = true;
- }
- }
- for (i = 0; i < gimple_asm_ninputs (stmt); ++i)
- {
- tree link = gimple_asm_input_op (stmt, i);
- tree op = TREE_VALUE (link);
- if (REFERENCE_CLASS_P (op)
- && (op = maybe_fold_reference (op, false)) != NULL_TREE)
- {
- TREE_VALUE (link) = op;
- changed = true;
- }
- }
+ {
+ size_t noutputs;
+ const char **oconstraints;
+ const char *constraint;
+ bool allows_mem, allows_reg;
+
+ noutputs = gimple_asm_noutputs (stmt);
+ oconstraints = XALLOCAVEC (const char *, noutputs);
+
+ for (i = 0; i < gimple_asm_noutputs (stmt); ++i)
+ {
+ tree link = gimple_asm_output_op (stmt, i);
+ tree op = TREE_VALUE (link);
+ oconstraints[i]
+ = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (link)));
+ if (REFERENCE_CLASS_P (op)
+ && (op = maybe_fold_reference (op, true)) != NULL_TREE)
+ {
+ TREE_VALUE (link) = op;
+ changed = true;
+ }
+ }
+ for (i = 0; i < gimple_asm_ninputs (stmt); ++i)
+ {
+ tree link = gimple_asm_input_op (stmt, i);
+ tree op = TREE_VALUE (link);
+ constraint
+ = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (link)));
+ parse_input_constraint (&constraint, 0, 0, noutputs, 0,
+ oconstraints, &allows_mem, &allows_reg);
+ if (REFERENCE_CLASS_P (op)
+ && (op = maybe_fold_reference (op, !allows_reg && allows_mem))
+ != NULL_TREE)
+ {
+ TREE_VALUE (link) = op;
+ changed = true;
+ }
+ }
+ }
break;
case GIMPLE_DEBUG:
--- gcc/testsuite/gcc.dg/pr50571.c.jj 2011-09-29 21:28:05.000000000 +0200
+++ gcc/testsuite/gcc.dg/pr50571.c 2011-09-29 21:30:08.000000000 +0200
@@ -0,0 +1,11 @@
+/* PR inline-asm/50571 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+static const int var[4] = { 1, 2, 3, 4 };
+
+void
+foo (void)
+{
+ __asm volatile ("" : : "m" (*(int *) var));
+}
Jakub
