When the operand is gimplified to an extract of a register or a
register we have to disallow memory as we otherwise fail to
gimplify it properly. Instead of
__asm__("" : "=rm" __imag <r>);
we want
__asm__("" : "=rm" D.2772);
_1 = REALPART_EXPR <r>;
r = COMPLEX_EXPR <_1, D.2772>;
otherwise SSA rewrite will fail and generate wrong code with 'r'
left bare in the asm output.
Bootstrap and regtest in progress on x86_64-unknown-linux-gnu.
I've made the testcase hopefully generic enough (the bug used =X
which I'm not sure is portable - I've used _Complex int so 'r'
has a chance to work).
OK?
Thanks,
Richard.
PR middle-end/115426
* gimplify.cc (gimplify_asm_expr): Handle "rm" output
constraint gimplified to a register (operation).
* gcc.dg/pr115426.c: New testcase.
---
gcc/gimplify.cc | 16 ++++++++++++++++
gcc/testsuite/gcc.dg/pr115426.c | 9 +++++++++
2 files changed, 25 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/pr115426.c
diff --git a/gcc/gimplify.cc b/gcc/gimplify.cc
index 04875e8df29..450be45422f 100644
--- a/gcc/gimplify.cc
+++ b/gcc/gimplify.cc
@@ -7044,6 +7044,22 @@ gimplify_asm_expr (tree *expr_p, gimple_seq *pre_p,
gimple_seq *post_p)
ret = tret;
}
+ /* If the gimplified operand is a register we do not allow memory. */
+ if (allows_mem
+ && (is_gimple_reg (TREE_VALUE (link))
+ || (handled_component_p (TREE_VALUE (link))
+ && is_gimple_reg (TREE_OPERAND (TREE_VALUE (link), 0)))))
+ {
+ if (allows_reg)
+ allows_mem = 0;
+ else
+ {
+ error ("impossible constraint in %<asm%>");
+ error ("non-memory output %d must stay in memory", i);
+ return GS_ERROR;
+ }
+ }
+
/* If the constraint does not allow memory make sure we gimplify
it to a register if it is not already but its base is. This
happens for complex and vector components. */
diff --git a/gcc/testsuite/gcc.dg/pr115426.c b/gcc/testsuite/gcc.dg/pr115426.c
new file mode 100644
index 00000000000..8432f102992
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr115426.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-std=gnu11" } */
+
+_Complex int fcs()
+{
+ _Complex int r;
+ __asm__("" : "=rm" (__imag__ r));
+ return r;
+}
--
2.35.3
