Fix PR middle-end/44993

Fix PR middle-end/44993

[Eric Botcazou]

[-- Attachment #1: Type: text/plain, Size: 1386 bytes --]

This is the bootstrap failure on SPARC64/Linux introduced by the fix for PR 
middle-end/44790, which was a bootstrap failure on IA-64/HP-UX introduced by 
the mem-ref2 merge.

The fix introduced a non-canonical expansion for MEM_REF via POINTER_PLUS_EXPR 
which bypasses checks for valid addresses in the SPARC back-end: 

  name = MEM[(struct
exp_ch3__make_predefined_primitive_specs__B_99__stream_op_tss_names___PAD
*)D.14526_1156 + 4294967296B];

is expanded into

        sethi   %hi(stream_op_tss_names.6060+4294967296), %l2
        or      %l2, %lo(stream_op_tss_names.6060+4294967296), %l2

which overflows since sethi is a 32-bit operator.

This can very likely happen for other back-ends as well so I think that the 
best approach is to fix PR middle-end/44790 more canonically.  The problem 
was that:

op0 = expand_expr (base, NULL_RTX, address_mode, EXPAND_NORMAL);

assumed that op0 was generated in address_mode; this isn't guaranteed so an 
explicit address conversion is required:

op0 = convert_memory_address_addr_space (address_mode, op0, as);


Bootstrapped/regtested on SPARC64/Linux, applied on the mainline as obvious.


2010-07-28  Eric Botcazou  <ebotcazou@adacore.com>

	PR middle-end/44790
	PR middle-end/44993
	* expr.c (expand_expr_real_1) <MEM_REF>: Revert latest change.  Make
	sure the base has address_mode before adding the offset.


-- 
Eric Botcazou

[-- Attachment #2: pr44993.diff --]
[-- Type: text/x-diff, Size: 980 bytes --]

Index: expr.c
===================================================================
--- expr.c	(revision 162566)
+++ expr.c	(working copy)
@@ -8730,11 +8730,14 @@ expand_expr_real_1 (tree exp, rtx target
 	  base = build2 (BIT_AND_EXPR, TREE_TYPE (base),
 			 gimple_assign_rhs1 (def_stmt),
 			 gimple_assign_rhs2 (def_stmt));
+	op0 = expand_expr (base, NULL_RTX, VOIDmode, EXPAND_NORMAL);
+	op0 = convert_memory_address_addr_space (address_mode, op0, as);
 	if (!integer_zerop (TREE_OPERAND (exp, 1)))
-	  base = build2 (POINTER_PLUS_EXPR, TREE_TYPE (base),
-			 base, double_int_to_tree (sizetype,
-						   mem_ref_offset (exp)));
-	op0 = expand_expr (base, NULL_RTX, address_mode, EXPAND_SUM);
+	  {
+	    rtx off
+	      = immed_double_int_const (mem_ref_offset (exp), address_mode);
+	    op0 = simplify_gen_binary (PLUS, address_mode, op0, off);
+	  }
 	op0 = memory_address_addr_space (mode, op0, as);
 	temp = gen_rtx_MEM (mode, op0);
 	set_mem_attributes (temp, exp, 0);

Re: Fix PR middle-end/44993

[H.J. Lu]

On Wed, Jul 28, 2010 at 12:44 AM, Eric Botcazou <ebotcazou@adacore.com> wrote:
> This is the bootstrap failure on SPARC64/Linux introduced by the fix for PR
> middle-end/44790, which was a bootstrap failure on IA-64/HP-UX introduced by
> the mem-ref2 merge.
>
> The fix introduced a non-canonical expansion for MEM_REF via POINTER_PLUS_EXPR
> which bypasses checks for valid addresses in the SPARC back-end:
>
>  name = MEM[(struct
> exp_ch3__make_predefined_primitive_specs__B_99__stream_op_tss_names___PAD
> *)D.14526_1156 + 4294967296B];
>
> is expanded into
>
>        sethi   %hi(stream_op_tss_names.6060+4294967296), %l2
>        or      %l2, %lo(stream_op_tss_names.6060+4294967296), %l2
>
> which overflows since sethi is a 32-bit operator.
>
> This can very likely happen for other back-ends as well so I think that the
> best approach is to fix PR middle-end/44790 more canonically.  The problem
> was that:
>
> op0 = expand_expr (base, NULL_RTX, address_mode, EXPAND_NORMAL);
>
> assumed that op0 was generated in address_mode; this isn't guaranteed so an
> explicit address conversion is required:
>
> op0 = convert_memory_address_addr_space (address_mode, op0, as);
>
>
> Bootstrapped/regtested on SPARC64/Linux, applied on the mainline as obvious.
>
>
> 2010-07-28  Eric Botcazou  <ebotcazou@adacore.com>
>
>        PR middle-end/44790
>        PR middle-end/44993
>        * expr.c (expand_expr_real_1) <MEM_REF>: Revert latest change.  Make
>        sure the base has address_mode before adding the offset.
>

This patch caused:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45670


-- 
H.J.

Re: Fix PR middle-end/44993

[Eric Botcazou]

> This patch caused:
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45670

No, it didn't, it cannot cause a code size regression from GCC 4.5 since it 
reverted an incorrect change made on trunk only.  Start from 161906 please.

-- 
Eric Botcazou

Re: Fix PR middle-end/44993

[Andrew Pinski]

On Tue, Sep 14, 2010 at 10:51 PM, Eric Botcazou <ebotcazou@adacore.com> wrote:
> No, it didn't, it cannot cause a code size regression from GCC 4.5 since it
> reverted an incorrect change made on trunk only.  Start from 161906 please.

By the way I noticed iv-opts differences between 4.3 and 4.6.  So you
might want to consider IV-opts changes first.

-- Pinski

Re: Fix PR middle-end/44993

[Eric Botcazou]

> This also caused:
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46252

Again, no, it didn't, it cannot cause a regression from GCC 4.5 since it 
reverted an incorrect change made on trunk only.

-- 
Eric Botcazou