[PATCH, PR 60556] Fix ICE on platforms with signed pointer extension.

[Jakub Jelinek]

On Thu, Mar 20, 2014 at 09:48:58AM -0700, Steve Ellcey  wrote:
> This patch fixes pr60556, a GCC ICE.  The problem is in convert_move where,
> if we are trying to put a 32 bit address into a 64 bit destination we
> can wind up calling emit_move_insn with NULL_RTX as a source.
> 
> The problem comes when creating fill_value.  If unsignedp is false
> then we call emit_store_flag to set fill_value.  If lowfrom is a symbol
> reference then emit_store_flag returns NULL_RTX (because symbol references
> are constant) and we wind up calling emit_move_insn with NULL_RTX as a
> source and getting an ICE.

I think the right fix is instead to use emit_store_flag_force, that will
force into register only when necessary, and will do so even in the numerous
other cases when emit_store_flag may return NULL (LABEL_REF, other
constants, different branch costs, etc.).

Will bootstrap/regtest this on x86_64-linux and i686-linux, Steve, can you
please test on mips?  Ok for trunk if testing passes?

2014-04-11  Steve Ellcey  <sellcey@mips.com>
	    Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/60556
	* expr.c (convert_move): Use emit_store_flag_force instead of
	emit_store_flag.  Pass lowpart_mode instead of VOIDmode as 5th
	argument to it.

	* gcc.c-torture/compile/pr60556.c: New test.

--- gcc/expr.c.jj	2014-03-28 23:06:44.000000000 +0100
+++ gcc/expr.c	2014-04-11 10:59:24.664014557 +0200
@@ -551,9 +551,9 @@ convert_move (rtx to, rtx from, int unsi
       if (unsignedp)
 	fill_value = const0_rtx;
       else
-	fill_value = emit_store_flag (gen_reg_rtx (word_mode),
-				      LT, lowfrom, const0_rtx,
-				      VOIDmode, 0, -1);
+	fill_value = emit_store_flag_force (gen_reg_rtx (word_mode),
+					    LT, lowfrom, const0_rtx,
+					    lowpart_mode, 0, -1);
 
       /* Fill the remaining words.  */
       for (i = GET_MODE_SIZE (lowpart_mode) / UNITS_PER_WORD; i < nwords; i++)
--- gcc/testsuite/gcc.c-torture/compile/pr60556.c.jj	2014-04-11 11:01:53.535218278 +0200
+++ gcc/testsuite/gcc.c-torture/compile/pr60556.c	2014-04-11 11:01:53.535218278 +0200
@@ -0,0 +1,8 @@
+/* PR middle-end/60556 */
+
+int g (int);
+
+unsigned long long f (void)
+{
+ return (unsigned long long)(long)&g;
+}

	Jakub