With the patch this time...
-------- Forwarded Message -------- Subject: [PATCH] Fix undefined behavior in h8300 backend Date: Mon, 21 Sep 2015 11:10:04 -0600 From: Jeff Law <l...@redhat.com> To: gcc-patches@gcc.gnu.org This was found when building all configurations using the trunk compiler. A run-of-the-mill problem with left shifting -1. To make sure I didn't muck anything up badly, I went back to Kazu's introduction of this pattern (2003), took his pseudo-code and turned it into a trivial h8300 specific test. I also verified newlib built with the new compiler. newlib never triggers this pattern though. I briefly pondered adding tests for the many other patterns Kazu added in 2003 as well as generalizing andsi3_ashift_n_lower, but I just couldn't justify that much time on the H8 port :-) Installed on the trunk. Jeff
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index c25888a..b6527de 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2015-09-21 Jeff Law <l...@redhat.com> + + * config/h8300/h8300.md (andsi3_ashift_n_lower): Avoid undefined + behavior. + 2015-09-21 Ulrich Weigand <ulrich.weig...@de.ibm.com> * config/spu/spu.c (spu_expand_insv): Avoid undefined behavior. diff --git a/gcc/config/h8300/h8300.md b/gcc/config/h8300/h8300.md index 4079b30..52213ac 100644 --- a/gcc/config/h8300/h8300.md +++ b/gcc/config/h8300/h8300.md @@ -3914,7 +3914,8 @@ (clobber (match_scratch:QI 4 "=X,&r"))] "(TARGET_H8300H || TARGET_H8300S) && INTVAL (operands[2]) <= 15 - && INTVAL (operands[3]) == ((-1 << INTVAL (operands[2])) & 0xffff)" + && UINTVAL (operands[3]) == ((HOST_WIDE_INT_M1U << INTVAL (operands[2])) + & 0xffff)" "#" "&& reload_completed" [(parallel [(set (match_dup 5) diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index c65469f..7afd523 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2015-09-21 Jeff Law <l...@redhat.com> + + * gcc.target/h8300/andsi3_ashift_n_lower.c: New test. + 2015-09-21 Ville Voutilainen <ville.voutilai...@gmail.com> Complete the implementation of N4230, Nested namespace definition. diff --git a/gcc/testsuite/gcc.target/h8300/andsi3_ashift_n_lower.c b/gcc/testsuite/gcc.target/h8300/andsi3_ashift_n_lower.c new file mode 100644 index 0000000..8cacc52 --- /dev/null +++ b/gcc/testsuite/gcc.target/h8300/andsi3_ashift_n_lower.c @@ -0,0 +1,7 @@ +/* { dg-do compile } */ +/* { dg-options "-mh -O2 -fomit-frame-pointer" } */ +/* { dg-final { scan-assembler-times "extu" 1 } } */ + +unsigned long foo(unsigned long a) + { return (a << 4) & 0xffff; } +