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

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