While it always seemed wrong to me that there's no way to avoid the
default "flags" and "fpsr" clobbers, the regression the fix for
PR/60663 introduced (see PR/63637) makes it even more desirable to have
such a mechanism: This way, at least asm()s with a single output and no
explicit clobbers can again be made subject to CSE.
gcc:
2014-10-31 Jan Beulich <jbeul...@suse.com>
* config/i386/i386.c (ix86_target_string): Add
-mno-default-asm-clobbers.
(ix86_valid_target_attribute_inner_p): Handle
-m{,no-}default-asm-clobbers.
(ix86_md_asm_clobbers): Handle "inverse" clobbers.
* config/i386/i386.h (NOCC_REGNUM, NOFPSR_REGNUM): Define.
(ADDITIONAL_REGISTER_NAMES): Add "cc", "!cc", "!flags", and
"!fpsr".
* config/i386/i386.opt: Add mdefault-asm-clobbers and
mno-default-asm-clobbers.
* varasm.c (decode_reg_name_and_count): Permit negative
register numbers in ADDITIONAL_REGISTER_NAMES.
gcc/testsuite:
2014-10-31 Jan Beulich <jbeul...@suse.com>
* gcc.target/i386/20060218-1.c: Adjust expected error.
* gcc.target/i386/invclbr[123].c: New.
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -2664,6 +2664,7 @@ ix86_target_string (HOST_WIDE_INT isa, i
{ "-minline-stringops-dynamically",
MASK_INLINE_STRINGOPS_DYNAMICALLY },
{ "-mms-bitfields", MASK_MS_BITFIELD_LAYOUT },
{ "-mno-align-stringops", MASK_NO_ALIGN_STRINGOPS },
+ { "-mno-default-asm-clobbers", MASK_NO_DEFAULT_ASM_CLOBBERS },
{ "-mno-fancy-math-387", MASK_NO_FANCY_MATH_387 },
{ "-mno-push-args", MASK_NO_PUSH_ARGS },
{ "-mno-red-zone", MASK_NO_RED_ZONE },
@@ -4649,6 +4650,10 @@ ix86_valid_target_attribute_inner_p (tre
OPT_mno_align_stringops,
MASK_NO_ALIGN_STRINGOPS),
+ IX86_ATTR_NO ("default-asm-clobbers",
+ OPT_mno_default_asm_clobbers,
+ MASK_NO_DEFAULT_ASM_CLOBBERS),
+
IX86_ATTR_YES ("recip",
OPT_mrecip,
MASK_RECIP),
@@ -44165,10 +44170,31 @@ ix86_c_mode_for_suffix (char suffix)
static tree
ix86_md_asm_clobbers (tree, tree, tree clobbers)
{
- clobbers = tree_cons (NULL_TREE, build_string (5, "flags"),
- clobbers);
- clobbers = tree_cons (NULL_TREE, build_string (4, "fpsr"),
- clobbers);
+ tree clobber;
+ bool flags_used = false, fpsr_used = false;
+ bool nocc_used = false, nofpsr_used = false;
+
+ if (!TARGET_DEFAULT_ASM_CLOBBERS)
+ return clobbers;
+
+ for (clobber = clobbers; clobber; clobber = TREE_CHAIN (clobber))
+ switch (decode_reg_name (TREE_STRING_POINTER (TREE_VALUE (clobber))))
+ {
+ case FLAGS_REG: flags_used = true; break;
+ case FPSR_REG: fpsr_used = true; break;
+ case NOCC_REGNUM: nocc_used = true; break;
+ case NOFPSR_REGNUM: nofpsr_used = true; break;
+ }
+
+ if ((flags_used && nocc_used) || (fpsr_used && nofpsr_used))
+ error ("conflicting clobbers in %<asm%>");
+
+ if (!flags_used && !nocc_used)
+ clobbers = tree_cons (NULL_TREE, build_string (5, "flags"),
+ clobbers);
+ if (!fpsr_used && !nofpsr_used)
+ clobbers = tree_cons (NULL_TREE, build_string (4, "fpsr"),
+ clobbers);
return clobbers;
}
--- a/gcc/config/i386/i386.h
+++ b/gcc/config/i386/i386.h
@@ -1242,6 +1242,11 @@ extern const char *host_detect_local_cpu
? INVALID_REGNUM \
: REAL_PIC_OFFSET_TABLE_REGNUM)
+/* Fake register numbers to be used as "inverse" asm() clobber specifiers.
+ Any negative numbers below the range used by decode_reg_name () will do. */
+#define NOCC_REGNUM (-127)
+#define NOFPSR_REGNUM (-126)
+
#define GOT_SYMBOL_NAME "_GLOBAL_OFFSET_TABLE_"
/* This is overridden by <cygwin.h>. */
@@ -2059,7 +2064,9 @@ do {
\
{ "zmm16", 53}, { "zmm17", 54}, { "zmm18", 55}, { "zmm19", 56}, \
{ "zmm20", 57}, { "zmm21", 58}, { "zmm22", 59}, { "zmm23", 60}, \
{ "zmm24", 61}, { "zmm25", 62}, { "zmm26", 63}, { "zmm27", 64}, \
- { "zmm28", 65}, { "zmm29", 66}, { "zmm30", 67}, { "zmm31", 68} }
+ { "zmm28", 65}, { "zmm29", 66}, { "zmm30", 67}, { "zmm31", 68}, \
+ { "cc", FLAGS_REG }, { "!cc", NOCC_REGNUM }, \
+ { "!flags", NOCC_REGNUM }, { "!fpsr", NOFPSR_REGNUM } }
/* Note we are omitting these since currently I don't know how
to get gcc to use these, since they want the same but different
--- a/gcc/config/i386/i386.opt
+++ b/gcc/config/i386/i386.opt
@@ -287,6 +287,10 @@ Enum(pmode) String(long) Value(PMODE_DI)
mcpu=
Target RejectNegative Joined Undocumented Alias(mtune=) Warn(%<-mcpu=%> is
deprecated; use %<-mtune=%> or %<-march=%> instead)
+mdefault-asm-clobbers
+Target RejectNegative Report InverseMask(NO_DEFAULT_ASM_CLOBBERS,
DEFAULT_ASM_CLOBBERS) Undocumented Save
+Attach compatibility clobbers (flags and fpsr) to every asm().
+
mfancy-math-387
Target RejectNegative Report InverseMask(NO_FANCY_MATH_387,
USE_FANCY_MATH_387) Save
Generate sin, cos, sqrt for FPU
@@ -355,6 +359,10 @@ Use native (MS) bitfield layout
mno-align-stringops
Target RejectNegative Report Mask(NO_ALIGN_STRINGOPS) Undocumented Save
+mno-default-asm-clobbers
+Target RejectNegative Report Mask(NO_DEFAULT_ASM_CLOBBERS) Save
+Don't attach compatibility clobbers (flags and fpsr) to every asm().
+
mno-fancy-math-387
Target RejectNegative Report Mask(NO_FANCY_MATH_387) Undocumented Save
--- a/gcc/testsuite/gcc.target/i386/20060218-1.c
+++ b/gcc/testsuite/gcc.target/i386/20060218-1.c
@@ -3,6 +3,6 @@
void
foo (void)
{
- register int cc __asm ("cc"); /* { dg-error "invalid register name" } */
+ register int cc __asm ("cc"); /* { dg-error "register specified .* not
general enough" } */
__asm ("" : : "r" (cc) : "cc");
}
--- a/gcc/testsuite/gcc.target/i386/invclbr1.c
+++ b/gcc/testsuite/gcc.target/i386/invclbr1.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+void test(void)
+{
+ asm ("" ::: "cc" );
+ asm ("" ::: "!cc" );
+ asm ("" ::: "flags" );
+ asm ("" ::: "!flags" );
+ asm ("" ::: "fpsr" );
+ asm ("" ::: "!fpsr" );
+
+ asm ("" ::: "cc", "!cc" ); /* { dg-error "conflicting clobbers" }
*/
+ asm ("" ::: "flags", "!cc" ); /* { dg-error "conflicting
clobbers" } */
+ asm ("" ::: "cc", "!flags" ); /* { dg-error "conflicting
clobbers" } */
+ asm ("" ::: "flags", "!flags" ); /* { dg-error "conflicting clobbers" }
*/
+ asm ("" ::: "fpsr", "!fpsr" ); /* { dg-error "conflicting clobbers" }
*/
+
+ asm ("" ::: "cc", "!fpsr" );
+ asm ("" ::: "flags", "!fpsr" );
+ asm ("" ::: "fpsr", "!flags" );
+ asm ("" ::: "fpsr", "!cc" );
+}
--- a/gcc/testsuite/gcc.target/i386/invclbr2.c
+++ b/gcc/testsuite/gcc.target/i386/invclbr2.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-fdump-rtl-expand" } */
+
+void test(void)
+{
+ asm ("" ::: "!cc", "!fpsr" );
+ asm ("" ::: "!fpsr", "!flags" );
+}
+
+/* { dg-final { scan-rtl-dump-not "clobber" "expand" } } */
+/* { dg-final { cleanup-rtl-dump "expand" } } */
--- a/gcc/testsuite/gcc.target/i386/invclbr3.c
+++ b/gcc/testsuite/gcc.target/i386/invclbr3.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-fdump-rtl-expand" } */
+
+void test(void)
+{
+ asm ("" ::: "!cc");
+ asm ("" ::: "!flags");
+ asm ("" ::: "!fpsr");
+}
+
+/* { dg-final { scan-rtl-dump-times "\\(clobber \\(reg\[^()\]* fpsr\\)\\)" 2
"expand" } } */
+/* { dg-final { scan-rtl-dump-times "\\(clobber \\(reg\[^()\]* flags\\)\\)" 1
"expand" } } */
+/* { dg-final { cleanup-rtl-dump "expand" } } */
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -936,7 +936,7 @@ decode_reg_name_and_count (const char *a
for (i = 0; i < (int) ARRAY_SIZE (table); i++)
if (table[i].name[0]
&& ! strcmp (asmspec, table[i].name)
- && reg_names[table[i].number][0])
+ && (table[i].number < 0 || reg_names[table[i].number][0]))
return table[i].number;
}
#endif /* ADDITIONAL_REGISTER_NAMES */
x86: allow to suppress default clobbers added to asm()s
While it always seemed wrong to me that there's no way to avoid the
default "flags" and "fpsr" clobbers, the regression the fix for
PR/60663 introduced (see PR/63637) makes it even more desirable to have
such a mechanism: This way, at least asm()s with a single output and no
explicit clobbers can again be made subject to CSE.
gcc:
2014-10-31 Jan Beulich <jbeul...@suse.com>
* config/i386/i386.c (ix86_target_string): Add
-mno-default-asm-clobbers.
(ix86_valid_target_attribute_inner_p): Handle
-m{,no-}default-asm-clobbers.
(ix86_md_asm_clobbers): Handle "inverse" clobbers.
* config/i386/i386.h (NOCC_REGNUM, NOFPSR_REGNUM): Define.
(ADDITIONAL_REGISTER_NAMES): Add "cc", "!cc", "!flags", and
"!fpsr".
* config/i386/i386.opt: Add mdefault-asm-clobbers and
mno-default-asm-clobbers.
* varasm.c (decode_reg_name_and_count): Permit negative
register numbers in ADDITIONAL_REGISTER_NAMES.
gcc/testsuite:
2014-10-31 Jan Beulich <jbeul...@suse.com>
* gcc.target/i386/20060218-1.c: Adjust expected error.
* gcc.target/i386/invclbr[123].c: New.
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -2664,6 +2664,7 @@ ix86_target_string (HOST_WIDE_INT isa, i
{ "-minline-stringops-dynamically",
MASK_INLINE_STRINGOPS_DYNAMICALLY },
{ "-mms-bitfields", MASK_MS_BITFIELD_LAYOUT },
{ "-mno-align-stringops", MASK_NO_ALIGN_STRINGOPS },
+ { "-mno-default-asm-clobbers", MASK_NO_DEFAULT_ASM_CLOBBERS },
{ "-mno-fancy-math-387", MASK_NO_FANCY_MATH_387 },
{ "-mno-push-args", MASK_NO_PUSH_ARGS },
{ "-mno-red-zone", MASK_NO_RED_ZONE },
@@ -4649,6 +4650,10 @@ ix86_valid_target_attribute_inner_p (tre
OPT_mno_align_stringops,
MASK_NO_ALIGN_STRINGOPS),
+ IX86_ATTR_NO ("default-asm-clobbers",
+ OPT_mno_default_asm_clobbers,
+ MASK_NO_DEFAULT_ASM_CLOBBERS),
+
IX86_ATTR_YES ("recip",
OPT_mrecip,
MASK_RECIP),
@@ -44165,10 +44170,31 @@ ix86_c_mode_for_suffix (char suffix)
static tree
ix86_md_asm_clobbers (tree, tree, tree clobbers)
{
- clobbers = tree_cons (NULL_TREE, build_string (5, "flags"),
- clobbers);
- clobbers = tree_cons (NULL_TREE, build_string (4, "fpsr"),
- clobbers);
+ tree clobber;
+ bool flags_used = false, fpsr_used = false;
+ bool nocc_used = false, nofpsr_used = false;
+
+ if (!TARGET_DEFAULT_ASM_CLOBBERS)
+ return clobbers;
+
+ for (clobber = clobbers; clobber; clobber = TREE_CHAIN (clobber))
+ switch (decode_reg_name (TREE_STRING_POINTER (TREE_VALUE (clobber))))
+ {
+ case FLAGS_REG: flags_used = true; break;
+ case FPSR_REG: fpsr_used = true; break;
+ case NOCC_REGNUM: nocc_used = true; break;
+ case NOFPSR_REGNUM: nofpsr_used = true; break;
+ }
+
+ if ((flags_used && nocc_used) || (fpsr_used && nofpsr_used))
+ error ("conflicting clobbers in %<asm%>");
+
+ if (!flags_used && !nocc_used)
+ clobbers = tree_cons (NULL_TREE, build_string (5, "flags"),
+ clobbers);
+ if (!fpsr_used && !nofpsr_used)
+ clobbers = tree_cons (NULL_TREE, build_string (4, "fpsr"),
+ clobbers);
return clobbers;
}
--- a/gcc/config/i386/i386.h
+++ b/gcc/config/i386/i386.h
@@ -1242,6 +1242,11 @@ extern const char *host_detect_local_cpu
? INVALID_REGNUM \
: REAL_PIC_OFFSET_TABLE_REGNUM)
+/* Fake register numbers to be used as "inverse" asm() clobber specifiers.
+ Any negative numbers below the range used by decode_reg_name () will do. */
+#define NOCC_REGNUM (-127)
+#define NOFPSR_REGNUM (-126)
+
#define GOT_SYMBOL_NAME "_GLOBAL_OFFSET_TABLE_"
/* This is overridden by <cygwin.h>. */
@@ -2059,7 +2064,9 @@ do {
\
{ "zmm16", 53}, { "zmm17", 54}, { "zmm18", 55}, { "zmm19", 56}, \
{ "zmm20", 57}, { "zmm21", 58}, { "zmm22", 59}, { "zmm23", 60}, \
{ "zmm24", 61}, { "zmm25", 62}, { "zmm26", 63}, { "zmm27", 64}, \
- { "zmm28", 65}, { "zmm29", 66}, { "zmm30", 67}, { "zmm31", 68} }
+ { "zmm28", 65}, { "zmm29", 66}, { "zmm30", 67}, { "zmm31", 68}, \
+ { "cc", FLAGS_REG }, { "!cc", NOCC_REGNUM }, \
+ { "!flags", NOCC_REGNUM }, { "!fpsr", NOFPSR_REGNUM } }
/* Note we are omitting these since currently I don't know how
to get gcc to use these, since they want the same but different
--- a/gcc/config/i386/i386.opt
+++ b/gcc/config/i386/i386.opt
@@ -287,6 +287,10 @@ Enum(pmode) String(long) Value(PMODE_DI)
mcpu=
Target RejectNegative Joined Undocumented Alias(mtune=) Warn(%<-mcpu=%> is
deprecated; use %<-mtune=%> or %<-march=%> instead)
+mdefault-asm-clobbers
+Target RejectNegative Report InverseMask(NO_DEFAULT_ASM_CLOBBERS,
DEFAULT_ASM_CLOBBERS) Undocumented Save
+Attach compatibility clobbers (flags and fpsr) to every asm().
+
mfancy-math-387
Target RejectNegative Report InverseMask(NO_FANCY_MATH_387,
USE_FANCY_MATH_387) Save
Generate sin, cos, sqrt for FPU
@@ -355,6 +359,10 @@ Use native (MS) bitfield layout
mno-align-stringops
Target RejectNegative Report Mask(NO_ALIGN_STRINGOPS) Undocumented Save
+mno-default-asm-clobbers
+Target RejectNegative Report Mask(NO_DEFAULT_ASM_CLOBBERS) Save
+Don't attach compatibility clobbers (flags and fpsr) to every asm().
+
mno-fancy-math-387
Target RejectNegative Report Mask(NO_FANCY_MATH_387) Undocumented Save
--- a/gcc/testsuite/gcc.target/i386/20060218-1.c
+++ b/gcc/testsuite/gcc.target/i386/20060218-1.c
@@ -3,6 +3,6 @@
void
foo (void)
{
- register int cc __asm ("cc"); /* { dg-error "invalid register name" } */
+ register int cc __asm ("cc"); /* { dg-error "register specified .* not
general enough" } */
__asm ("" : : "r" (cc) : "cc");
}
--- a/gcc/testsuite/gcc.target/i386/invclbr1.c
+++ b/gcc/testsuite/gcc.target/i386/invclbr1.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+void test(void)
+{
+ asm ("" ::: "cc" );
+ asm ("" ::: "!cc" );
+ asm ("" ::: "flags" );
+ asm ("" ::: "!flags" );
+ asm ("" ::: "fpsr" );
+ asm ("" ::: "!fpsr" );
+
+ asm ("" ::: "cc", "!cc" ); /* { dg-error "conflicting clobbers" }
*/
+ asm ("" ::: "flags", "!cc" ); /* { dg-error "conflicting
clobbers" } */
+ asm ("" ::: "cc", "!flags" ); /* { dg-error "conflicting
clobbers" } */
+ asm ("" ::: "flags", "!flags" ); /* { dg-error "conflicting clobbers" }
*/
+ asm ("" ::: "fpsr", "!fpsr" ); /* { dg-error "conflicting clobbers" }
*/
+
+ asm ("" ::: "cc", "!fpsr" );
+ asm ("" ::: "flags", "!fpsr" );
+ asm ("" ::: "fpsr", "!flags" );
+ asm ("" ::: "fpsr", "!cc" );
+}
--- a/gcc/testsuite/gcc.target/i386/invclbr2.c
+++ b/gcc/testsuite/gcc.target/i386/invclbr2.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-fdump-rtl-expand" } */
+
+void test(void)
+{
+ asm ("" ::: "!cc", "!fpsr" );
+ asm ("" ::: "!fpsr", "!flags" );
+}
+
+/* { dg-final { scan-rtl-dump-not "clobber" "expand" } } */
+/* { dg-final { cleanup-rtl-dump "expand" } } */
--- a/gcc/testsuite/gcc.target/i386/invclbr3.c
+++ b/gcc/testsuite/gcc.target/i386/invclbr3.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-fdump-rtl-expand" } */
+
+void test(void)
+{
+ asm ("" ::: "!cc");
+ asm ("" ::: "!flags");
+ asm ("" ::: "!fpsr");
+}
+
+/* { dg-final { scan-rtl-dump-times "\\(clobber \\(reg\[^()\]* fpsr\\)\\)" 2
"expand" } } */
+/* { dg-final { scan-rtl-dump-times "\\(clobber \\(reg\[^()\]* flags\\)\\)" 1
"expand" } } */
+/* { dg-final { cleanup-rtl-dump "expand" } } */
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -936,7 +936,7 @@ decode_reg_name_and_count (const char *a
for (i = 0; i < (int) ARRAY_SIZE (table); i++)
if (table[i].name[0]
&& ! strcmp (asmspec, table[i].name)
- && reg_names[table[i].number][0])
+ && (table[i].number < 0 || reg_names[table[i].number][0]))
return table[i].number;
}
#endif /* ADDITIONAL_REGISTER_NAMES */
