[PATCH] Fix asm X constraint (PR inline-asm/59155)

[Bernd Edlinger <bernd dot edlinger at hotmail dot de>]

Hi!

This restricts the X constraint in asm statements, which
can be easily folded by combine in something completely
invalid.

It is necessary to allow scratch here, because on i386
the md_asm_adjust hook inserts them.

The second test case fails because lra does not
allow all register for anything_ok operands (aka X)
and later it fails to match the two X constraints
in case '0': if (curr_alt[m] == NO_REGS) break.

There is also an identical bug in the reload pass,
but I do not know how to fix that, as it is almost
used nowhere today.


Boot-strapped and regression-tested on x86_64-pc-linux-gnu.
OK for trunk?


Thanks
Bernd.

Attachment: changelog-pr59155.txt
Description: changelog-pr59155.txt

Index: gcc/lra-constraints.c
===================================================================
--- gcc/lra-constraints.c	(revision 236569)
+++ gcc/lra-constraints.c	(working copy)
@@ -1854,7 +1854,7 @@ process_alt_operands (int only_alternative)
 	  if (curr_static_id->operand_alternative[opalt_num].anything_ok)
 	    {
 	      /* Fast track for no constraints at all.	*/
-	      curr_alt[nop] = NO_REGS;
+	      curr_alt[nop] = ALL_REGS;
 	      CLEAR_HARD_REG_SET (curr_alt_set[nop]);
 	      curr_alt_win[nop] = true;
 	      curr_alt_match_win[nop] = false;
Index: gcc/recog.c
===================================================================
--- gcc/recog.c	(revision 236569)
+++ gcc/recog.c	(working copy)
@@ -1757,6 +1757,10 @@ asm_operand_ok (rtx op, const char *constraint, co
 	    result = 1;
 	  break;
 
+	case 'X':
+	  if (scratch_operand (op, VOIDmode))
+	    result = 1;
+	  /* ... fall through ...  */
 	case 'g':
 	  if (general_operand (op, VOIDmode))
 	    result = 1;
Index: gcc/testsuite/gcc.dg/torture/pr59155-1.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr59155-1.c	(revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr59155-1.c	(working copy)
@@ -0,0 +1,7 @@
+double f(double x){
+  asm volatile("":"+X"(x));
+  return x;
+}
+double g(double x,double y){
+  return f(f(x)+f(y));
+}
Index: gcc/testsuite/gcc.dg/torture/pr59155-2.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr59155-2.c	(revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr59155-2.c	(working copy)
@@ -0,0 +1,7 @@
+double f(double x){
+  asm volatile("":"+X"(x));
+  return x;
+}
+double g(){
+  return f(1.);
+}
Index: gcc/testsuite/gcc.dg/torture/pr59155-3.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr59155-3.c	(revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr59155-3.c	(working copy)
@@ -0,0 +1,27 @@
+void
+noprop1 (int **x, int y, int z)
+{
+  int *ptr = *x + y * z / 11;
+  asm volatile ("noprop1 %0" : : "X" (*ptr));
+}
+
+void
+noprop2 (int **x, int y, int z)
+{
+  int *ptr = *x + y * z / 11;
+  asm volatile ("noprop2 %0" : : "X" (ptr));
+}
+
+int *global_var;
+
+void
+const1 (void)
+{
+  asm volatile ("const1 %0" : : "X" (global_var));
+}
+
+void
+const2 (void)
+{
+  asm volatile ("const2 %0" : : "X" (*global_var));
+}