On Fri, Nov 22, 2024 at 12:01:21AM +0000, Joseph Myers wrote:
> On Mon, 18 Nov 2024, Jakub Jelinek wrote:
>
> > +@smallexample
> > +extern void foo (void), bar (void);
> > +int v;
> > +extern int w;
> > +asm (".globl %cc0, %cc2; .text; %cc0: call %cc1; ret; .data; %cc2: .word
> > %cc3"
> > + :: ":" (foo), "-s" (&bar), ":" (&w), "-i" (&v));
> > +@end smallexample
> > +
> > +This asm declaration tells the compiler it defines function foo and
> > variable
> > +w and uses function bar and variable v. This will compile even with PIC,
> > +but it is up to the user to ensure it will assemble correctly and have the
> > +expected behavior.
>
> That should be @code{foo}, @code{w}, @code{bar}, @code{v}.
>
> The C front-end changes in this patch are OK.
Thanks, here is the adjusted patch.
2024-11-21 Jakub Jelinek <ja...@redhat.com>
PR c/41045
gcc/
* stmt.cc (parse_output_constraint, parse_input_constraint): Handle
- modifier.
* recog.h (raw_constraint_p): Declare.
* recog.cc (raw_constraint_p): New variable.
(asm_operand_ok, constrain_operands): Handle - modifier.
* common.md (i, s, n): For raw_constraint_p don't require
LEGITIMATE_PIC_OPERAND_P.
* doc/md.texi: Document - constraint modifier.
gcc/c/
* c-typeck.cc (build_asm_expr): Reject - constraint modifier inside
of a function.
gcc/cp/
* semantics.cc (finish_asm_stmt): Reject - constraint modifier inside
of a function.
gcc/testsuite/
* c-c++-common/toplevel-asm-4.c: Add missing %cc2 use in template, add
bar, x, &y operands with "-i" and "-s" constraints.
(x, y): New variables.
(bar): Declare.
* c-c++-common/toplevel-asm-7.c: New test.
* c-c++-common/toplevel-asm-8.c: New test.
--- gcc/stmt.cc.jj 2024-11-17 21:07:06.712510933 -1100
+++ gcc/stmt.cc 2024-11-17 21:45:30.201294501 -1100
@@ -269,7 +269,7 @@ parse_output_constraint (const char **co
case 'E': case 'F': case 'G': case 'H':
case 's': case 'i': case 'n':
case 'I': case 'J': case 'K': case 'L': case 'M':
- case 'N': case 'O': case 'P': case ',':
+ case 'N': case 'O': case 'P': case ',': case '-':
break;
case '0': case '1': case '2': case '3': case '4':
@@ -364,7 +364,7 @@ parse_input_constraint (const char **con
case 'E': case 'F': case 'G': case 'H':
case 's': case 'i': case 'n':
case 'I': case 'J': case 'K': case 'L': case 'M':
- case 'N': case 'O': case 'P': case ',':
+ case 'N': case 'O': case 'P': case ',': case '-':
break;
case ':':
--- gcc/recog.h.jj 2024-08-15 09:23:26.981012468 -1100
+++ gcc/recog.h 2024-11-17 22:26:47.190602347 -1100
@@ -335,6 +335,9 @@ private:
matched. */
extern int which_alternative;
+/* True for inline asm operands with - constraint modifier. */
+extern bool raw_constraint_p;
+
/* The following vectors hold the results from insn_extract. */
struct recog_data_d
--- gcc/recog.cc.jj 2024-10-24 21:00:29.511767242 -1100
+++ gcc/recog.cc 2024-11-17 23:16:00.654874432 -1100
@@ -86,6 +86,9 @@ static operand_alternative asm_op_alt[MA
int which_alternative;
+/* True for inline asm operands with - constraint modifier. */
+bool raw_constraint_p;
+
/* Nonzero after end of reload pass.
Set to 1 or 0 by toplev.cc.
Controls the significance of (SUBREG (MEM)). */
@@ -2300,6 +2303,7 @@ asm_operand_ok (rtx op, const char *cons
switch (c)
{
case ',':
+ raw_constraint_p = false;
constraint++;
continue;
@@ -2350,6 +2354,11 @@ asm_operand_ok (rtx op, const char *cons
result = 1;
break;
+ case '-':
+ raw_constraint_p = true;
+ constraint++;
+ continue;
+
case '<':
case '>':
/* ??? Before auto-inc-dec, auto inc/dec insns are not supposed
@@ -2407,8 +2416,12 @@ asm_operand_ok (rtx op, const char *cons
constraint++;
while (--len && *constraint && *constraint != ',');
if (len)
- return 0;
+ {
+ raw_constraint_p = false;
+ return 0;
+ }
}
+ raw_constraint_p = false;
/* For operands without < or > constraints reject side-effects. */
if (AUTO_INC_DEC && !incdec_ok && result && MEM_P (op))
@@ -3202,6 +3215,9 @@ constrain_operands (int strict, alternat
case ',':
c = '\0';
break;
+ case '-':
+ raw_constraint_p = true;
+ break;
case '#':
/* Ignore rest of this alternative as far as
@@ -3357,6 +3373,7 @@ constrain_operands (int strict, alternat
}
while (p += len, c);
+ raw_constraint_p = false;
constraints[opno] = p;
/* If this operand did not win somehow,
this alternative loses. */
--- gcc/common.md.jj 2024-11-17 21:07:06.712510933 -1100
+++ gcc/common.md 2024-11-17 22:33:23.805858947 -1100
@@ -92,13 +92,13 @@ (define_address_constraint "p"
(define_constraint "i"
"Matches a general integer constant."
(and (match_test "CONSTANT_P (op)")
- (match_test "!flag_pic || LEGITIMATE_PIC_OPERAND_P (op)")))
+ (match_test "!flag_pic || raw_constraint_p || LEGITIMATE_PIC_OPERAND_P
(op)")))
(define_constraint "s"
"Matches a symbolic integer constant."
(and (match_test "CONSTANT_P (op)")
(match_test "!CONST_SCALAR_INT_P (op)")
- (match_test "!flag_pic || LEGITIMATE_PIC_OPERAND_P (op)")))
+ (match_test "!flag_pic || raw_constraint_p || LEGITIMATE_PIC_OPERAND_P
(op)")))
(define_constraint ":"
"Defines a symbol."
@@ -108,7 +108,7 @@ (define_constraint ":"
(define_constraint "n"
"Matches a non-symbolic integer constant."
(and (match_test "CONST_SCALAR_INT_P (op)")
- (match_test "!flag_pic || LEGITIMATE_PIC_OPERAND_P (op)")))
+ (match_test "!flag_pic || raw_constraint_p || LEGITIMATE_PIC_OPERAND_P
(op)")))
(define_constraint "E"
"Matches a floating-point constant."
--- gcc/doc/md.texi.jj 2024-11-17 21:07:19.843326980 -1100
+++ gcc/doc/md.texi 2024-11-17 23:43:12.301073998 -1100
@@ -1889,6 +1889,28 @@ (define_insn "extendhisi2"
@dots{})
@end smallexample
@end ifset
+
+@cindex @samp{-} in constraint
+@item -
+Says that the selected following constraints within the same alternative
+should be matched differently. Normally in PIC code symbolic operands
+in constraints like @samp{i}, @samp{s} or @samp{n} are not allowed at all
+or severely restricted. The @samp{-} modifier, which is only allowed
+outside of functions, allows symbolic operands even in PIC code. This
+modifier is usually used together with the @code{cc} operand modifier.
+
+@smallexample
+extern void foo (void), bar (void);
+int v;
+extern int w;
+asm (".globl %cc0, %cc2; .text; %cc0: call %cc1; ret; .data; %cc2: .word %cc3"
+ :: ":" (foo), "-s" (&bar), ":" (&w), "-i" (&v));
+@end smallexample
+
+This asm declaration tells the compiler it defines function @code{foo} and
+variable @code{w} and uses function @code{bar} and variable @code{v}. This
+will compile even with PIC, but it is up to the user to ensure it will
+assemble correctly and have the expected behavior.
@end table
@node Machine Constraints
--- gcc/c/c-typeck.cc.jj 2024-11-17 21:07:06.000000000 -1100
+++ gcc/c/c-typeck.cc 2024-11-17 22:17:13.935708652 -1100
@@ -12281,6 +12281,11 @@ build_asm_expr (location_t loc, tree str
}
}
}
+ else if (output != error_mark_node && strstr (constraint, "-"))
+ {
+ error_at (loc, "%<-%> modifier used inside of a function");
+ output = error_mark_node;
+ }
TREE_VALUE (tail) = output;
}
@@ -12365,6 +12370,11 @@ build_asm_expr (location_t loc, tree str
}
}
}
+ else if (input != error_mark_node && strstr (constraint, "-"))
+ {
+ error_at (loc, "%<-%> modifier used inside of a function");
+ input = error_mark_node;
+ }
TREE_VALUE (tail) = input;
}
--- gcc/cp/semantics.cc.jj 2024-11-17 21:07:06.718510849 -1100
+++ gcc/cp/semantics.cc 2024-11-17 22:24:24.469669093 -1100
@@ -2255,6 +2255,11 @@ finish_asm_stmt (location_t loc, int vol
}
}
}
+ else if (operand != error_mark_node && strstr (constraint, "-"))
+ {
+ error_at (loc, "%<-%> modifier used inside of a function");
+ operand = error_mark_node;
+ }
TREE_VALUE (t) = operand;
}
@@ -2382,6 +2387,11 @@ finish_asm_stmt (location_t loc, int vol
}
}
}
+ else if (operand != error_mark_node && strstr (constraint, "-"))
+ {
+ error_at (loc, "%<-%> modifier used inside of a function");
+ operand = error_mark_node;
+ }
TREE_VALUE (t) = operand;
}
--- gcc/testsuite/c-c++-common/toplevel-asm-4.c.jj 2024-11-17
21:07:19.844326965 -1100
+++ gcc/testsuite/c-c++-common/toplevel-asm-4.c 2024-11-17 23:41:10.340778042
-1100
@@ -3,6 +3,8 @@
/* { dg-options "-O0" } */
extern int v[42], w;
+int x[42], y;
void foo (void);
+void bar (void) {}
-asm ("# %cc0: %cc1:" :: ":" (foo), ":" (v), ":" (&w));
+asm ("# %cc0: %cc1: %cc2: %cc3 %cc4 %cc5" :: ":" (foo), ":" (v), ":" (&w),
"-i" (bar), "-s" (x), "-s" (&y));
--- gcc/testsuite/c-c++-common/toplevel-asm-7.c.jj 2024-11-17
23:37:58.518458202 -1100
+++ gcc/testsuite/c-c++-common/toplevel-asm-7.c 2024-11-17 23:39:01.531577774
-1100
@@ -0,0 +1,16 @@
+/* PR c/41045 */
+/* { dg-do compile } */
+/* { dg-options "-O0" } */
+/* { dg-additional-options "-fpic" { target fpic } } */
+
+struct S { char a; long long b; int c; };
+enum E { E0, E1 = sizeof (struct S) + 15 };
+int v[42];
+void foo (void) {}
+
+asm ("# %0 %1 %2 %cc3 %cc4 %% %="
+ :: "i" (sizeof (struct S)),
+ "i" (__builtin_offsetof (struct S, c)),
+ "i" (E1),
+ "-s" (foo),
+ "-i" (v));
--- gcc/testsuite/c-c++-common/toplevel-asm-8.c.jj 2024-11-17
23:39:39.794043169 -1100
+++ gcc/testsuite/c-c++-common/toplevel-asm-8.c 2024-11-17 23:51:53.656789127
-1100
@@ -0,0 +1,13 @@
+/* PR c/41045 */
+/* { dg-do compile } */
+/* { dg-options "-O0" } */
+
+void
+foo (void)
+{
+ int m;
+ asm ("" : "=-m" (m)); /* { dg-error "'-' modifier used inside
of a function" } */
+ asm ("" : : "-m" (m)); /* { dg-error "'-' modifier used inside of a
function" } */
+ asm ("" : : "-i" (32)); /* { dg-error "'-' modifier used inside of a
function" } */
+ asm ("" : : "-s" (foo)); /* { dg-error "'-' modifier used inside of a
function" } */
+}
Jakub
