[PATCH] expand: EXTEND_BITINT CALL_EXPR results [PR114332]

[PATCH] expand: EXTEND_BITINT CALL_EXPR results [PR114332]

[Jakub Jelinek]

Hi!

The x86-64 and aarch64 psABIs (and the unwritten ia64 psABI part) say that
the padding bits of _BitInt are undefined, while the expansion internally
typically assumes that non-mode precision integers are sign/zero extended
and extends after operations.  We handle that mismatch with EXTEND_BITINT
done when reading from untrusted sources like function arguments, reading
_BitInt from memory etc. but otherwise keep relying on stuff being extended
internally (say in pseudos).
The return value of a function is an ABI boundary though too and we need
to extend that too.

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

2024-03-15  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/114332
	* expr.cc (expand_expr_real_1): EXTEND_BITINT also CALL_EXPR results.

--- gcc/expr.cc.jj	2024-03-04 19:20:27.120200885 +0100
+++ gcc/expr.cc	2024-03-14 19:22:50.623550538 +0100
@@ -12350,7 +12350,8 @@ expand_expr_real_1 (tree exp, rtx target
 	    return expand_builtin (exp, target, subtarget, tmode, ignore);
 	  }
       }
-      return expand_call (exp, target, ignore);
+      temp = expand_call (exp, target, ignore);
+      return EXTEND_BITINT (temp);
 
     case VIEW_CONVERT_EXPR:
       op0 = NULL_RTX;
--- gcc/testsuite/gcc.dg/torture/bitint-64.c.jj	2024-03-14 19:50:41.051311949 +0100
+++ gcc/testsuite/gcc.dg/torture/bitint-64.c	2024-03-14 19:50:05.480806808 +0100
@@ -0,0 +1,22 @@
+/* PR middle-end/114332 */
+/* { dg-do run { target bitint } } */
+/* { dg-options "-std=c23 -fwrapv" } */
+/* { dg-skip-if "" { ! run_expensive_tests }  { "*" } { "-O0" "-O2" } } */
+/* { dg-skip-if "" { ! run_expensive_tests } { "-flto" } { "" } } */
+
+enum E { E22 = 22 } e = E22;
+
+_BitInt (5)
+foo (void)
+{
+  _Atomic _BitInt (5) b = 0;
+  b += e;
+  return b;
+}
+
+int
+main ()
+{
+  if (foo () != -10)
+    __builtin_abort ();
+}

	Jakub

Re: [PATCH] expand: EXTEND_BITINT CALL_EXPR results [PR114332]

[Richard Biener]

On Fri, 15 Mar 2024, Jakub Jelinek wrote:

> Hi!
> 
> The x86-64 and aarch64 psABIs (and the unwritten ia64 psABI part) say that
> the padding bits of _BitInt are undefined, while the expansion internally
> typically assumes that non-mode precision integers are sign/zero extended
> and extends after operations.  We handle that mismatch with EXTEND_BITINT
> done when reading from untrusted sources like function arguments, reading
> _BitInt from memory etc. but otherwise keep relying on stuff being extended
> internally (say in pseudos).
> The return value of a function is an ABI boundary though too and we need
> to extend that too.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

OK.

> 2024-03-15  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR middle-end/114332
> 	* expr.cc (expand_expr_real_1): EXTEND_BITINT also CALL_EXPR results.
> 
> --- gcc/expr.cc.jj	2024-03-04 19:20:27.120200885 +0100
> +++ gcc/expr.cc	2024-03-14 19:22:50.623550538 +0100
> @@ -12350,7 +12350,8 @@ expand_expr_real_1 (tree exp, rtx target
>  	    return expand_builtin (exp, target, subtarget, tmode, ignore);
>  	  }
>        }
> -      return expand_call (exp, target, ignore);
> +      temp = expand_call (exp, target, ignore);
> +      return EXTEND_BITINT (temp);
>  
>      case VIEW_CONVERT_EXPR:
>        op0 = NULL_RTX;
> --- gcc/testsuite/gcc.dg/torture/bitint-64.c.jj	2024-03-14 19:50:41.051311949 +0100
> +++ gcc/testsuite/gcc.dg/torture/bitint-64.c	2024-03-14 19:50:05.480806808 +0100
> @@ -0,0 +1,22 @@
> +/* PR middle-end/114332 */
> +/* { dg-do run { target bitint } } */
> +/* { dg-options "-std=c23 -fwrapv" } */
> +/* { dg-skip-if "" { ! run_expensive_tests }  { "*" } { "-O0" "-O2" } } */
> +/* { dg-skip-if "" { ! run_expensive_tests } { "-flto" } { "" } } */
> +
> +enum E { E22 = 22 } e = E22;
> +
> +_BitInt (5)
> +foo (void)
> +{
> +  _Atomic _BitInt (5) b = 0;
> +  b += e;
> +  return b;
> +}
> +
> +int
> +main ()
> +{
> +  if (foo () != -10)
> +    __builtin_abort ();
> +}
> 
> 	Jakub
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)