diff mbox series

internal-fn: Temporarily disable flag_trapv during .{ADD,SUB,MUL}_OVERFLOW etc. expansion [PR114753]

Message ID ZiDKBlshfMzwvnuY@tucnak
State New
Headers show
Series internal-fn: Temporarily disable flag_trapv during .{ADD,SUB,MUL}_OVERFLOW etc. expansion [PR114753] | expand

Commit Message

Jakub Jelinek April 18, 2024, 7:21 a.m. UTC
Hi!

__builtin_{add,sub,mul}_overflow{,_p} builtins are well defined
for all inputs even for -ftrapv, and the -fsanitize=signed-integer-overflow
ifns shouldn't abort in libgcc but emit the desired ubsan diagnostics
or abort depending on -fsanitize* setting regardless of -ftrapv.
The expansion of these internal functions uses expand_expr* in various
places (e.g. MULT_EXPR at least in 2 spots), so temporarily disabling
flag_trapv in all those spots would be hard.
The following patch disables it around the bodies of 3 functions
which can do the expand_expr calls.
If it was in the C++ FE, I'd use some RAII sentinel, but I don't think
we have one in the middle-end.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2024-04-18  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/114753
	* internal-fn.cc (expand_mul_overflow): Save flag_trapv and
	temporarily clear it for the duration of the function, then
	restore previous value.
	(expand_vector_ubsan_overflow): Likewise.
	(expand_arith_overflow): Likewise.

	* gcc.dg/pr114753.c: New test.


	Jakub

Comments

Richard Biener April 18, 2024, 7:39 a.m. UTC | #1
On Thu, 18 Apr 2024, Jakub Jelinek wrote:

> Hi!
> 
> __builtin_{add,sub,mul}_overflow{,_p} builtins are well defined
> for all inputs even for -ftrapv, and the -fsanitize=signed-integer-overflow
> ifns shouldn't abort in libgcc but emit the desired ubsan diagnostics
> or abort depending on -fsanitize* setting regardless of -ftrapv.
> The expansion of these internal functions uses expand_expr* in various
> places (e.g. MULT_EXPR at least in 2 spots), so temporarily disabling
> flag_trapv in all those spots would be hard.
> The following patch disables it around the bodies of 3 functions
> which can do the expand_expr calls.
> If it was in the C++ FE, I'd use some RAII sentinel, but I don't think
> we have one in the middle-end.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

OK.

Thanks,
Richard.

> 2024-04-18  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR middle-end/114753
> 	* internal-fn.cc (expand_mul_overflow): Save flag_trapv and
> 	temporarily clear it for the duration of the function, then
> 	restore previous value.
> 	(expand_vector_ubsan_overflow): Likewise.
> 	(expand_arith_overflow): Likewise.
> 
> 	* gcc.dg/pr114753.c: New test.
> 
> --- gcc/internal-fn.cc.jj	2024-03-23 08:22:50.490607002 +0100
> +++ gcc/internal-fn.cc	2024-04-17 13:44:21.673594413 +0200
> @@ -1631,7 +1631,11 @@ expand_mul_overflow (location_t loc, tre
>    rtx target = NULL_RTX;
>    signop sign;
>    enum insn_code icode;
> +  int save_flag_trapv = flag_trapv;
>  
> +  /* We don't want any __mulv?i3 etc. calls from the expansion of
> +     these internal functions, so disable -ftrapv temporarily.  */
> +  flag_trapv = 0;
>    done_label = gen_label_rtx ();
>    do_error = gen_label_rtx ();
>  
> @@ -2479,6 +2483,7 @@ expand_mul_overflow (location_t loc, tre
>        else
>  	expand_arith_overflow_result_store (lhs, target, mode, res);
>      }
> +  flag_trapv = save_flag_trapv;
>  }
>  
>  /* Expand UBSAN_CHECK_* internal function if it has vector operands.  */
> @@ -2499,7 +2504,11 @@ expand_vector_ubsan_overflow (location_t
>    rtx resvr = NULL_RTX;
>    unsigned HOST_WIDE_INT const_cnt = 0;
>    bool use_loop_p = (!cnt.is_constant (&const_cnt) || const_cnt > 4);
> +  int save_flag_trapv = flag_trapv;
>  
> +  /* We don't want any __mulv?i3 etc. calls from the expansion of
> +     these internal functions, so disable -ftrapv temporarily.  */
> +  flag_trapv = 0;
>    if (lhs)
>      {
>        optab op;
> @@ -2629,6 +2638,7 @@ expand_vector_ubsan_overflow (location_t
>      }
>    else if (resvr)
>      emit_move_insn (lhsr, resvr);
> +  flag_trapv = save_flag_trapv;
>  }
>  
>  /* Expand UBSAN_CHECK_ADD call STMT.  */
> @@ -2707,7 +2717,11 @@ expand_arith_overflow (enum tree_code co
>    prec0 = MIN (prec0, pr);
>    pr = get_min_precision (arg1, uns1_p ? UNSIGNED : SIGNED);
>    prec1 = MIN (prec1, pr);
> +  int save_flag_trapv = flag_trapv;
>  
> +  /* We don't want any __mulv?i3 etc. calls from the expansion of
> +     these internal functions, so disable -ftrapv temporarily.  */
> +  flag_trapv = 0;
>    /* If uns0_p && uns1_p, precop is minimum needed precision
>       of unsigned type to hold the exact result, otherwise
>       precop is minimum needed precision of signed type to
> @@ -2748,6 +2762,7 @@ expand_arith_overflow (enum tree_code co
>  	  ops.location = loc;
>  	  rtx tem = expand_expr_real_2 (&ops, NULL_RTX, mode, EXPAND_NORMAL);
>  	  expand_arith_overflow_result_store (lhs, target, mode, tem);
> +	  flag_trapv = save_flag_trapv;
>  	  return;
>  	}
>  
> @@ -2771,6 +2786,7 @@ expand_arith_overflow (enum tree_code co
>  	      if (integer_zerop (arg0) && !unsr_p)
>  		{
>  		  expand_neg_overflow (loc, lhs, arg1, false, NULL);
> +		  flag_trapv = save_flag_trapv;
>  		  return;
>  		}
>  	      /* FALLTHRU */
> @@ -2781,6 +2797,7 @@ expand_arith_overflow (enum tree_code co
>  	    case MULT_EXPR:
>  	      expand_mul_overflow (loc, lhs, arg0, arg1, unsr_p,
>  				   unsr_p, unsr_p, false, NULL);
> +	      flag_trapv = save_flag_trapv;
>  	      return;
>  	    default:
>  	      gcc_unreachable ();
> @@ -2826,6 +2843,7 @@ expand_arith_overflow (enum tree_code co
>  	  else
>  	    expand_mul_overflow (loc, lhs, arg0, arg1, unsr_p,
>  				 uns0_p, uns1_p, false, NULL);
> +	  flag_trapv = save_flag_trapv;
>  	  return;
>  	}
>  
> --- gcc/testsuite/gcc.dg/pr114753.c.jj	2024-04-17 13:55:16.246482369 +0200
> +++ gcc/testsuite/gcc.dg/pr114753.c	2024-04-17 13:54:14.035352376 +0200
> @@ -0,0 +1,14 @@
> +/* PR middle-end/114753 */
> +/* { dg-do run } */
> +/* { dg-options "-O2 -ftrapv" } */
> +
> +int
> +main ()
> +{
> +  volatile long long i = __LONG_LONG_MAX__;
> +  volatile long long j = 2;
> +  long long k;
> +  if (!__builtin_mul_overflow (i, j, &k) || k != -2LL)
> +    __builtin_abort ();
> +  return 0;
> +}
> 
> 	Jakub
> 
>
diff mbox series

Patch

--- gcc/internal-fn.cc.jj	2024-03-23 08:22:50.490607002 +0100
+++ gcc/internal-fn.cc	2024-04-17 13:44:21.673594413 +0200
@@ -1631,7 +1631,11 @@  expand_mul_overflow (location_t loc, tre
   rtx target = NULL_RTX;
   signop sign;
   enum insn_code icode;
+  int save_flag_trapv = flag_trapv;
 
+  /* We don't want any __mulv?i3 etc. calls from the expansion of
+     these internal functions, so disable -ftrapv temporarily.  */
+  flag_trapv = 0;
   done_label = gen_label_rtx ();
   do_error = gen_label_rtx ();
 
@@ -2479,6 +2483,7 @@  expand_mul_overflow (location_t loc, tre
       else
 	expand_arith_overflow_result_store (lhs, target, mode, res);
     }
+  flag_trapv = save_flag_trapv;
 }
 
 /* Expand UBSAN_CHECK_* internal function if it has vector operands.  */
@@ -2499,7 +2504,11 @@  expand_vector_ubsan_overflow (location_t
   rtx resvr = NULL_RTX;
   unsigned HOST_WIDE_INT const_cnt = 0;
   bool use_loop_p = (!cnt.is_constant (&const_cnt) || const_cnt > 4);
+  int save_flag_trapv = flag_trapv;
 
+  /* We don't want any __mulv?i3 etc. calls from the expansion of
+     these internal functions, so disable -ftrapv temporarily.  */
+  flag_trapv = 0;
   if (lhs)
     {
       optab op;
@@ -2629,6 +2638,7 @@  expand_vector_ubsan_overflow (location_t
     }
   else if (resvr)
     emit_move_insn (lhsr, resvr);
+  flag_trapv = save_flag_trapv;
 }
 
 /* Expand UBSAN_CHECK_ADD call STMT.  */
@@ -2707,7 +2717,11 @@  expand_arith_overflow (enum tree_code co
   prec0 = MIN (prec0, pr);
   pr = get_min_precision (arg1, uns1_p ? UNSIGNED : SIGNED);
   prec1 = MIN (prec1, pr);
+  int save_flag_trapv = flag_trapv;
 
+  /* We don't want any __mulv?i3 etc. calls from the expansion of
+     these internal functions, so disable -ftrapv temporarily.  */
+  flag_trapv = 0;
   /* If uns0_p && uns1_p, precop is minimum needed precision
      of unsigned type to hold the exact result, otherwise
      precop is minimum needed precision of signed type to
@@ -2748,6 +2762,7 @@  expand_arith_overflow (enum tree_code co
 	  ops.location = loc;
 	  rtx tem = expand_expr_real_2 (&ops, NULL_RTX, mode, EXPAND_NORMAL);
 	  expand_arith_overflow_result_store (lhs, target, mode, tem);
+	  flag_trapv = save_flag_trapv;
 	  return;
 	}
 
@@ -2771,6 +2786,7 @@  expand_arith_overflow (enum tree_code co
 	      if (integer_zerop (arg0) && !unsr_p)
 		{
 		  expand_neg_overflow (loc, lhs, arg1, false, NULL);
+		  flag_trapv = save_flag_trapv;
 		  return;
 		}
 	      /* FALLTHRU */
@@ -2781,6 +2797,7 @@  expand_arith_overflow (enum tree_code co
 	    case MULT_EXPR:
 	      expand_mul_overflow (loc, lhs, arg0, arg1, unsr_p,
 				   unsr_p, unsr_p, false, NULL);
+	      flag_trapv = save_flag_trapv;
 	      return;
 	    default:
 	      gcc_unreachable ();
@@ -2826,6 +2843,7 @@  expand_arith_overflow (enum tree_code co
 	  else
 	    expand_mul_overflow (loc, lhs, arg0, arg1, unsr_p,
 				 uns0_p, uns1_p, false, NULL);
+	  flag_trapv = save_flag_trapv;
 	  return;
 	}
 
--- gcc/testsuite/gcc.dg/pr114753.c.jj	2024-04-17 13:55:16.246482369 +0200
+++ gcc/testsuite/gcc.dg/pr114753.c	2024-04-17 13:54:14.035352376 +0200
@@ -0,0 +1,14 @@ 
+/* PR middle-end/114753 */
+/* { dg-do run } */
+/* { dg-options "-O2 -ftrapv" } */
+
+int
+main ()
+{
+  volatile long long i = __LONG_LONG_MAX__;
+  volatile long long j = 2;
+  long long k;
+  if (!__builtin_mul_overflow (i, j, &k) || k != -2LL)
+    __builtin_abort ();
+  return 0;
+}