Hi! Several of the functions in the following testcases ICE. Unlike C++ FE, C FE doesn't error out on void type derefs right away, just warns. But using void type expression for "r" or "=r" doesn't make sense and was ICEing. The patch still tollerates it for constraints that allow only mem, as that case wasn't crashing and just address of it was presented to the asm.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? 2011-04-11 Jakub Jelinek <ja...@redhat.com> PR c/48552 * c-typeck.c (build_asm_expr): Error out on attempts to use void type outputs or inputs for constraints that allow reg or don't allow memory. * gcc.dg/pr48552-1.c: New test. * gcc.dg/pr48552-2.c: New test. --- gcc/c-typeck.c.jj 2011-03-31 08:51:03.000000000 +0200 +++ gcc/c-typeck.c 2011-04-11 13:29:17.000000000 +0200 @@ -8502,6 +8502,13 @@ build_asm_expr (location_t loc, tree str mark it addressable. */ if (!allows_reg && !c_mark_addressable (output)) output = error_mark_node; + if (!(!allows_reg && allows_mem) + && output != error_mark_node + && VOID_TYPE_P (TREE_TYPE (output))) + { + error_at (loc, "invalid use of void expression"); + output = error_mark_node; + } } else output = error_mark_node; @@ -8528,7 +8535,12 @@ build_asm_expr (location_t loc, tree str STRIP_NOPS (input); if (!c_mark_addressable (input)) input = error_mark_node; - } + } + else if (input != error_mark_node && VOID_TYPE_P (TREE_TYPE (input))) + { + error_at (loc, "invalid use of void expression"); + input = error_mark_node; + } } else input = error_mark_node; --- gcc/testsuite/gcc.dg/pr48552-1.c.jj 2011-04-11 14:22:13.000000000 +0200 +++ gcc/testsuite/gcc.dg/pr48552-1.c 2011-04-11 14:24:40.000000000 +0200 @@ -0,0 +1,53 @@ +/* PR c/48552 */ +/* { dg-do compile } */ +/* { dg-options "" } */ + +struct S; + +void +f1 (void *x) +{ + __asm volatile ("" : : "r" (*x)); /* { dg-warning "dereferencing" } */ +} /* { dg-error "invalid use of void expression" "" { target *-*-* } 10 } */ + +void +f2 (void *x) +{ + __asm volatile ("" : "=r" (*x)); /* { dg-warning "dereferencing" } */ +} /* { dg-error "invalid use of void expression" "" { target *-*-* } 16 } */ + /* { dg-error "invalid lvalue in asm output 0" "" { target *-*-* } 16 } */ +void +f3 (void *x) +{ + __asm volatile ("" : : "m" (*x)); /* { dg-warning "dereferencing" } */ +} + +void +f4 (void *x) +{ + __asm volatile ("" : "=m" (*x)); /* { dg-warning "dereferencing" } */ +} + +void +f5 (void *x) +{ + __asm volatile ("" : : "g" (*x)); /* { dg-warning "dereferencing" } */ +} /* { dg-error "invalid use of void expression" "" { target *-*-* } 34 } */ + +void +f6 (void *x) +{ + __asm volatile ("" : "=g" (*x)); /* { dg-warning "dereferencing" } */ +} /* { dg-error "invalid use of void expression" "" { target *-*-* } 40 } */ + /* { dg-error "invalid lvalue in asm output 0" "" { target *-*-* } 40 } */ +void +f7 (struct S *x) +{ + __asm volatile ("" : : "r" (*x)); /* { dg-error "dereferencing pointer to incomplete type" } */ +} + +void +f8 (struct S *x) +{ + __asm volatile ("" : "=r" (*x)); /* { dg-error "dereferencing pointer to incomplete type" } */ +} /* { dg-error "invalid lvalue in asm output 0" "" { target *-*-* } 52 } */ --- gcc/testsuite/gcc.dg/pr48552-2.c.jj 2011-04-11 14:22:13.000000000 +0200 +++ gcc/testsuite/gcc.dg/pr48552-2.c 2011-04-11 14:24:59.000000000 +0200 @@ -0,0 +1,53 @@ +/* PR c/48552 */ +/* { dg-do compile } */ +/* { dg-options "" } */ + +struct S; + +void +f1 (void *x) +{ + __asm ("" : : "r" (*x)); /* { dg-warning "dereferencing" } */ +} /* { dg-error "invalid use of void expression" "" { target *-*-* } 10 } */ + +void +f2 (void *x) +{ + __asm ("" : "=r" (*x)); /* { dg-warning "dereferencing" } */ +} /* { dg-error "invalid use of void expression" "" { target *-*-* } 16 } */ + /* { dg-error "invalid lvalue in asm output 0" "" { target *-*-* } 16 } */ +void +f3 (void *x) +{ + __asm ("" : : "m" (*x)); /* { dg-warning "dereferencing" } */ +} + +void +f4 (void *x) +{ + __asm ("" : "=m" (*x)); /* { dg-warning "dereferencing" } */ +} + +void +f5 (void *x) +{ + __asm ("" : : "g" (*x)); /* { dg-warning "dereferencing" } */ +} /* { dg-error "invalid use of void expression" "" { target *-*-* } 34 } */ + +void +f6 (void *x) +{ + __asm ("" : "=g" (*x)); /* { dg-warning "dereferencing" } */ +} /* { dg-error "invalid use of void expression" "" { target *-*-* } 40 } */ + /* { dg-error "invalid lvalue in asm output 0" "" { target *-*-* } 40 } */ +void +f7 (struct S *x) +{ + __asm ("" : : "r" (*x)); /* { dg-error "dereferencing pointer to incomplete type" } */ +} + +void +f8 (struct S *x) +{ + __asm ("" : "=r" (*x)); /* { dg-error "dereferencing pointer to incomplete type" } */ +} /* { dg-error "invalid lvalue in asm output 0" "" { target *-*-* } 52 } */ Jakub