Hi!
The following testcase is miscompiled on powerpc64le-linux at -O1 and higher
(except for -Og). The bug was introduced in r12-3252-gcad36f38576a6a7
which for SIGN_EXTEND from SUBREG_PROMOTED_SIGNED_P SUBREG used
SUBREG_PROMOTED_SET (temp, 1) (but that makes temp
SUBREG_PROMOTED_UNSIGNED_P because SRP_UNSIGNED is 1) and similarly the
ZERO_EXTEND from SUBREG_PROMOTED_UNSIGNED_P SUBREG used
SUBREG_PROMOTED_SET (temp, 0) (but that makes temp
SUBREG_PROMOTED_SIGNED_P because SRP_SIGNED is 0).
The following patch fixes that (swaps the 0s and 1s), but for better
readability uses the SRP_* constants.
rtl.h has:
/* Valid for subregs which are SUBREG_PROMOTED_VAR_P(). In that case
this gives the necessary extensions:
0 - signed (SPR_SIGNED)
1 - normal unsigned (SPR_UNSIGNED)
2 - value is both sign and unsign extended for mode
(SPR_SIGNED_AND_UNSIGNED).
-1 - pointer unsigned, which most often can be handled like unsigned
extension, except for generating instructions where we need to
emit special code (ptr_extend insns) on some architectures
(SPR_POINTER). */
The expr.c change in the same commit looks ok to me (passes unsignedp
to SUBREG_PROMOTED_SET, so 0 for signed, 1 for unsigned).
Starting bootstrap/regtest on powerpc64{,le}-linux now, ok for trunk?
2022-03-08 Jakub Jelinek <ja...@redhat.com>
PR rtl-optimization/104839
* simplify-rtx.cc (simplify_unary_operation_1) <case SIGN_EXTEND>:
Use SRP_SIGNED instead of incorrect 1 in SUBREG_PROMOTED_SET.
(simplify_unary_operation_1) <case ZERO_EXTEND>: Use SRP_UNSIGNED
instead of incorrect 0 in SUBREG_PROMOTED_SET.
* gcc.c-torture/execute/pr104839.c: New test.
--- gcc/simplify-rtx.cc.jj 2022-02-23 09:17:04.000000000 +0100
+++ gcc/simplify-rtx.cc 2022-03-08 16:31:20.823246404 +0100
@@ -1527,7 +1527,7 @@ simplify_context::simplify_unary_operati
if (partial_subreg_p (temp))
{
SUBREG_PROMOTED_VAR_P (temp) = 1;
- SUBREG_PROMOTED_SET (temp, 1);
+ SUBREG_PROMOTED_SET (temp, SRP_SIGNED);
}
return temp;
}
@@ -1662,7 +1662,7 @@ simplify_context::simplify_unary_operati
if (partial_subreg_p (temp))
{
SUBREG_PROMOTED_VAR_P (temp) = 1;
- SUBREG_PROMOTED_SET (temp, 0);
+ SUBREG_PROMOTED_SET (temp, SRP_UNSIGNED);
}
return temp;
}
--- gcc/testsuite/gcc.c-torture/execute/pr104839.c.jj 2022-03-08
16:46:51.418440078 +0100
+++ gcc/testsuite/gcc.c-torture/execute/pr104839.c 2022-03-08
16:46:27.044774203 +0100
@@ -0,0 +1,37 @@
+/* PR rtl-optimization/104839 */
+
+__attribute__((noipa)) short
+foo (void)
+{
+ return -1;
+}
+
+__attribute__((noipa)) int
+bar (void)
+{
+ short i = foo ();
+ if (i == -2)
+ return 2;
+ long k = i;
+ int j = -1;
+ volatile long s = 300;
+ if (k < 0)
+ {
+ k += s;
+ if (k < 0)
+ j = 0;
+ }
+ else if (k >= s)
+ j = 0;
+ if (j != -1)
+ return 1;
+ return 0;
+}
+
+int
+main ()
+{
+ if (bar () != 0)
+ __builtin_abort ();
+ return 0;
+}
Jakub
