* doc/md.texi: Document the new PowerPC "es" constraint.
Document that "m" can include automodified addresses on this target,
and explain how %U must be used. Extend the "Q" and "Z" documentation
to suggest "es" as well as "m".
* config/rs6000/constraints.md (es): New memory constraint.
(Q, Z): Update strings to match new documentation.
gcc/testsuite/
* gcc.target/powerpc/asm-es-1.c: New test.
* gcc.target/powerpc/asm-es-2.c: Likewise.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@149766
138bc75d-0d04-0410-961f-
82ee72b054a4
2009-07-18 Richard Sandiford <r.sandiford@uk.ibm.com>
+ * doc/md.texi: Document the new PowerPC "es" constraint.
+ Document that "m" can include automodified addresses on this target,
+ and explain how %U must be used. Extend the "Q" and "Z" documentation
+ to suggest "es" as well as "m".
+ * config/rs6000/constraints.md (es): New memory constraint.
+ (Q, Z): Update strings to match new documentation.
+
+2009-07-18 Richard Sandiford <r.sandiford@uk.ibm.com>
+
* config/rs6000/rs6000.c (rs6000_mode_dependent_address): Allow any
offset from virtual_stack_vars_rtx and arg_pointer_rtx.
* config/rs6000/predicates.md (volatile_mem_operand): Use
;; Memory constraints
+(define_memory_constraint "es"
+ "A ``stable'' memory operand; that is, one which does not include any
+automodification of the base register. Unlike @samp{m}, this constraint
+can be used in @code{asm} statements that might access the operand
+several times, or that might not access it at all."
+ (and (match_code "mem")
+ (match_test "GET_RTX_CLASS (GET_CODE (XEXP (op, 0))) != RTX_AUTOINC")))
+
(define_memory_constraint "Q"
- "Memory operand that is just an offset from a reg"
+ "Memory operand that is an offset from a register (it is usually better
+to use @samp{m} or @samp{es} in @code{asm} statements)"
(and (match_code "mem")
(match_test "GET_CODE (XEXP (op, 0)) == REG")))
(match_operand 0 "word_offset_memref_operand"))
(define_memory_constraint "Z"
- "Indexed or indirect memory operand"
+ "Memory operand that is an indexed or indirect from a register (it is
+usually better to use @samp{m} or @samp{es} in @code{asm} statements)"
(match_operand 0 "indexed_or_indirect_operand"))
;; Address constraints
Integer/Floating point constant that can be loaded into a register using
three instructions
+@item m
+Memory operand. Note that on PowerPC targets, @code{m} can include
+addresses that update the base register. It is therefore only safe
+to use @samp{m} in an @code{asm} statement if that @code{asm} statement
+accesses the operand exactly once. The @code{asm} statement must also
+use @samp{%U@var{<opno>}} as a placeholder for the ``update'' flag in the
+corresponding load or store instruction. For example:
+
+@smallexample
+asm ("st%U0 %1,%0" : "=m" (mem) : "r" (val));
+@end smallexample
+
+is correct but:
+
+@smallexample
+asm ("st %1,%0" : "=m" (mem) : "r" (val));
+@end smallexample
+
+is not. Use @code{es} rather than @code{m} if you don't want the
+base register to be updated.
+
+@item es
+A ``stable'' memory operand; that is, one which does not include any
+automodification of the base register. Unlike @samp{m}, this constraint
+can be used in @code{asm} statements that might access the operand
+several times, or that might not access it at all.
+
@item Q
-Memory operand that is an offset from a register (@samp{m} is preferable
-for @code{asm} statements)
+Memory operand that is an offset from a register (it is usually better
+to use @samp{m} or @samp{es} in @code{asm} statements)
@item Z
-Memory operand that is an indexed or indirect from a register (@samp{m} is
-preferable for @code{asm} statements)
+Memory operand that is an indexed or indirect from a register (it is
+usually better to use @samp{m} or @samp{es} in @code{asm} statements)
@item R
AIX TOC entry
+2009-07-18 Richard Sandiford <r.sandiford@uk.ibm.com>
+
+ * gcc.target/powerpc/asm-es-1.c: New test.
+ * gcc.target/powerpc/asm-es-2.c: Likewise.
+
2009-07-17 Richard Guenther <rguenther@suse.de>
PR c/40401
--- /dev/null
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+static inline void __attribute__((always_inline))
+f1 (void)
+{
+ long unused;
+ asm volatile ("" : "=es" (unused) :: "memory");
+}
+
+static void __attribute__((noinline))
+f2 (long *val)
+{
+ *val = 0x1234;
+}
+
+static long __attribute__((noinline))
+test (void)
+{
+ f1 ();
+ {
+ long val;
+ f2 (&val);
+ return val;
+ }
+}
+
+int
+main (void)
+{
+ return test () != 0x1234;
+}
--- /dev/null
+/* { dg-options "-O2" } */
+void
+f1 (int *p, int x)
+{
+ asm ("asm1 %0" : "=es" (p[x]));
+}
+
+void
+f2 (int *p)
+{
+ while (1)
+ {
+ p += 4;
+ asm ("asm2%U0 %0" : "=m" (*p));
+ }
+}
+
+void
+f3 (int *p)
+{
+ while (1)
+ {
+ p += 4;
+ asm ("asm3%U0 %0" : "=es" (*p));
+ }
+}
+
+void
+f4 (int *p)
+{
+ asm ("asm4 %0" : "=es" (p[100]));
+}
+
+/* { dg-final { scan-assembler "asm1 3,4" } } */
+/* { dg-final { scan-assembler "asm2u 16\\(3\\)" } } */
+/* { dg-final { scan-assembler "asm3 0\\(3\\)" } } */
+/* { dg-final { scan-assembler "asm4 400\\(3\\)" } } */