Fix gcc.c-torture/execute/20030928-1.c for ARM VxWorks

Fix gcc.c-torture/execute/20030928-1.c for ARM VxWorks

[Richard Sandiford]

This patch fixes gcc.c-torture/execute/20030928-1.c for ARM VxWorks
kernels.  We tried to create "symbol + big offset" constants, which
runs into the problems described in the patch.

The fix is along the same lines as that used for ColdFire uClinux.
I think it would come in useful for ARM uClinux too.

Richard


gcc/
	* config/arm/arm-protos.h (arm_cannot_force_const_mem): Declare.
	* config/arm/arm.c (TARGET_CANNOT_FORCE_CONST_MEM): Redefine to
	arm_cannot_force_const_mem.
	(arm_cannot_force_const_mem): New function.
	* config/arm/arm.h (ARM_OFFSETS_MUST_BE_WITHIN_SECTIONS_P): New macro.
	(LEGITIMATE_CONSTANT_P): Test arm_cannot_force_const_mem instead
	of arm_tls_referenced_p.
	* config/arm/arm.md (movsi): Split out-of-section constants when
	ARM_OFFSETS_MUST_BE_WITHIN_SECTIONS_P.
	* config/arm/vxworks.h (ARM_OFFSETS_MUST_BE_WITHIN_SECTIONS_P): Define.

Index: gcc/config/arm/arm-protos.h
===================================================================
--- gcc/config/arm/arm-protos.h	2007-07-04 02:07:24.000000000 -0700
+++ gcc/config/arm/arm-protos.h	2007-07-04 02:47:40.000000000 -0700
@@ -70,6 +70,7 @@ extern int neg_const_double_rtx_ok_for_f
 extern enum reg_class coproc_secondary_reload_class (enum machine_mode, rtx,
 						     bool);
 extern bool arm_tls_referenced_p (rtx);
+extern bool arm_cannot_force_const_mem (rtx);
 
 extern int cirrus_memory_offset (rtx);
 extern int arm_coproc_mem_operand (rtx, bool);
Index: gcc/config/arm/arm.c
===================================================================
--- gcc/config/arm/arm.c	2007-07-04 02:07:24.000000000 -0700
+++ gcc/config/arm/arm.c	2007-07-04 02:47:40.000000000 -0700
@@ -377,7 +377,7 @@ #define TARGET_HAVE_TLS true
 #endif
 
 #undef TARGET_CANNOT_FORCE_CONST_MEM
-#define TARGET_CANNOT_FORCE_CONST_MEM arm_tls_referenced_p
+#define TARGET_CANNOT_FORCE_CONST_MEM arm_cannot_force_const_mem
 
 #ifdef HAVE_AS_TLS
 #undef TARGET_ASM_OUTPUT_DWARF_DTPREL
@@ -4580,6 +4580,23 @@ arm_tls_referenced_p (rtx x)
 
   return for_each_rtx (&x, arm_tls_operand_p_1, NULL);
 }
+
+/* Implement TARGET_CANNOT_FORCE_CONST_MEM.  */
+
+bool
+arm_cannot_force_const_mem (rtx x)
+{
+  rtx base, offset;
+
+  if (ARM_OFFSETS_MUST_BE_WITHIN_SECTIONS_P)
+    {
+      split_const (x, &base, &offset);
+      if (GET_CODE (base) == SYMBOL_REF
+	  && !offset_within_block_p (base, INTVAL (offset)))
+	return true;
+    }
+  return arm_tls_referenced_p (x);
+}
 \f
 #define REG_OR_SUBREG_REG(X)						\
   (GET_CODE (X) == REG							\
Index: gcc/config/arm/arm.h
===================================================================
--- gcc/config/arm/arm.h	2007-07-04 02:07:24.000000000 -0700
+++ gcc/config/arm/arm.h	2007-07-04 02:47:40.000000000 -0700
@@ -1827,6 +1827,10 @@ #define CONSTANT_ADDRESS_P(X)  			\
 
 #endif /* AOF_ASSEMBLER */
 
+/* True if SYMBOL + OFFSET constants must refer to something within
+   SYMBOL's section.  */
+#define ARM_OFFSETS_MUST_BE_WITHIN_SECTIONS_P 0
+
 /* Nonzero if the constant value X is a legitimate general operand.
    It is given that X satisfies CONSTANT_P or is a CONST_DOUBLE.
 
@@ -1844,7 +1848,7 @@ #define THUMB_LEGITIMATE_CONSTANT_P(X)	\
   || flag_pic)
 
 #define LEGITIMATE_CONSTANT_P(X)			\
-  (!arm_tls_referenced_p (X)				\
+  (!arm_cannot_force_const_mem (X)			\
    && (TARGET_32BIT ? ARM_LEGITIMATE_CONSTANT_P (X)	\
 		    : THUMB_LEGITIMATE_CONSTANT_P (X)))
 
Index: gcc/config/arm/arm.md
===================================================================
--- gcc/config/arm/arm.md	2007-07-04 02:07:24.000000000 -0700
+++ gcc/config/arm/arm.md	2007-07-04 02:47:40.000000000 -0700
@@ -4649,6 +4649,8 @@ (define_expand "movsi"
         (match_operand:SI 1 "general_operand" ""))]
   "TARGET_EITHER"
   "
+  rtx base, offset, tmp;
+
   if (TARGET_32BIT)
     {
       /* Everything except mem = const or mem = mem can be done easily.  */
@@ -4674,6 +4676,19 @@ (define_expand "movsi"
         }
     }
 
+  if (ARM_OFFSETS_MUST_BE_WITHIN_SECTIONS_P)
+    {
+      split_const (operands[1], &base, &offset);
+      if (GET_CODE (base) == SYMBOL_REF
+	  && !offset_within_block_p (base, INTVAL (offset)))
+	{
+	  tmp = no_new_pseudos ? operands[0] : gen_reg_rtx (SImode);
+	  emit_move_insn (tmp, base);
+	  emit_insn (gen_addsi3 (operands[0], tmp, offset));
+	  DONE;
+	}
+    }
+
   /* Recognize the case where operand[1] is a reference to thread-local
      data and load its address to a register.  */
   if (arm_tls_referenced_p (operands[1]))
Index: gcc/config/arm/vxworks.h
===================================================================
--- gcc/config/arm/vxworks.h	2007-07-04 02:32:40.000000000 -0700
+++ gcc/config/arm/vxworks.h	2007-07-04 02:53:12.000000000 -0700
@@ -106,3 +106,11 @@ #define FUNCTION_PROFILER VXWORKS_FUNCTI
    the past before this macro was changed.  */
 #undef DEFAULT_STRUCTURE_SIZE_BOUNDARY
 #define DEFAULT_STRUCTURE_SIZE_BOUNDARY 8
+
+/* The kernel loader does not allow relocations to overflow, so we
+   cannot allow arbitrary relocation addends in kernel modules or RTP
+   executables.  Also, the dynamic loader uses the resolved relocation
+   value to distinguish references to the text and data segments, so we
+   cannot allow arbitrary offsets for shared libraries either.  */
+#undef ARM_OFFSETS_MUST_BE_WITHIN_SECTIONS_P
+#define ARM_OFFSETS_MUST_BE_WITHIN_SECTIONS_P 1

Re: Fix gcc.c-torture/execute/20030928-1.c for ARM VxWorks

[Mark Mitchell]

Richard Sandiford wrote:

> gcc/
> 	* config/arm/arm-protos.h (arm_cannot_force_const_mem): Declare.
> 	* config/arm/arm.c (TARGET_CANNOT_FORCE_CONST_MEM): Redefine to
> 	arm_cannot_force_const_mem.
> 	(arm_cannot_force_const_mem): New function.
> 	* config/arm/arm.h (ARM_OFFSETS_MUST_BE_WITHIN_SECTIONS_P): New macro.
> 	(LEGITIMATE_CONSTANT_P): Test arm_cannot_force_const_mem instead
> 	of arm_tls_referenced_p.
> 	* config/arm/arm.md (movsi): Split out-of-section constants when
> 	ARM_OFFSETS_MUST_BE_WITHIN_SECTIONS_P.
> 	* config/arm/vxworks.h (ARM_OFFSETS_MUST_BE_WITHIN_SECTIONS_P): Define.

Paul, would you review this, please?

Thanks,

-- 
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713

Re: Fix gcc.c-torture/execute/20030928-1.c for ARM VxWorks

[Paul Brook]

On Wednesday 04 July 2007, Richard Sandiford wrote:
> This patch fixes gcc.c-torture/execute/20030928-1.c for ARM VxWorks
> kernels.  We tried to create "symbol + big offset" constants, which
> runs into the problems described in the patch.

This seems like something there should be a target independent knob for. 
Apparently there isn't though, so ok.

Paul

Re: Fix gcc.c-torture/execute/20030928-1.c for ARM VxWorks

[Richard Sandiford]

Richard Earnshaw <Richard.Earnshaw@arm.com> writes:
> On Wed, 2007-07-04 at 10:55 +0100, Richard Sandiford wrote:
>> This patch fixes gcc.c-torture/execute/20030928-1.c for ARM VxWorks
>> kernels.  We tried to create "symbol + big offset" constants, which
>> runs into the problems described in the patch.
>> 
>> The fix is along the same lines as that used for ColdFire uClinux.
>> I think it would come in useful for ARM uClinux too.
>> 
>> Richard
>> 
>> 
>> gcc/
> [...]
>> 	* config/arm/arm.md (movsi): Split out-of-section constants when
>> 	ARM_OFFSETS_MUST_BE_WITHIN_SECTIONS_P.
>
> This breaks the build, since it contains a reference to the now-defunct
> no_new_pseudos.

Fixed with the patch below.  Tested by building cc1 on arm-eabi,
installed as obvious.  FYI, I had to disable werror because
of an unrelated signed/unsigned comparison warning in
arm.c:thumb1_compute_save_reg_mask, but I've left that alone.

Richard


gcc/
	* config/arm/arm.md (movsi): Use can_create_pseudo_p instead of
	no_new_pseudos.

Index: gcc/config/arm/arm.md
===================================================================
--- gcc/config/arm/arm.md	(revision 126797)
+++ gcc/config/arm/arm.md	(working copy)
@@ -4682,7 +4682,7 @@ (define_expand "movsi"
       if (GET_CODE (base) == SYMBOL_REF
 	  && !offset_within_block_p (base, INTVAL (offset)))
 	{
-	  tmp = no_new_pseudos ? operands[0] : gen_reg_rtx (SImode);
+	  tmp = can_create_pseudo_p () ? gen_reg_rtx (SImode) : operands[0];
 	  emit_move_insn (tmp, base);
 	  emit_insn (gen_addsi3 (operands[0], tmp, offset));
 	  DONE;