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From: Michael Meissner <meissner@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc(refs/users/meissner/heads/work139)] Update ChangeLog.meissner Date: Thu, 12 Oct 2023 21:54:23 +0000 (GMT) [thread overview] Message-ID: <20231012215423.654ED3856DC0@sourceware.org> (raw) https://gcc.gnu.org/g:448688aaf59f866c3dbd5c3d0e3c764147f37fb7 commit 448688aaf59f866c3dbd5c3d0e3c764147f37fb7 Author: Michael Meissner <meissner@linux.ibm.com> Date: Thu Oct 12 00:51:50 2023 -0400 Update ChangeLog.meissner Diff: --- gcc/ChangeLog.meissner | 28 ++++++++++++++++------------ 1 file changed, 16 insertions(+), 12 deletions(-) diff --git a/gcc/ChangeLog.meissner b/gcc/ChangeLog.meissner index 5021e3ab1f2..0075b9b4ee0 100644 --- a/gcc/ChangeLog.meissner +++ b/gcc/ChangeLog.meissner @@ -1,4 +1,4 @@ -==================== Branch work139, patch #1 ==================== +==================== Branch work139, patch #2 ==================== PowerPC: Do not depend on an undefined shift @@ -11,15 +11,15 @@ fine. I traced this down to a change made around October 10th: -commit 8f1a70a4fbcc6441c70da60d4ef6db1e5635e18a (HEAD) -Author: Jiufu Guo <guojiufu@linux.ibm.com> -Date: Tue Jan 10 20:52:33 2023 +0800 - - rs6000: build constant via li/lis;rldicl/rldicr - - If a constant is possible left/right cleaned on a rotated value from - a negative value of "li/lis". Then, using "li/lis ; rldicl/rldicr" - to build the constant. +| commit 8f1a70a4fbcc6441c70da60d4ef6db1e5635e18a (HEAD) +| Author: Jiufu Guo <guojiufu@linux.ibm.com> +| Date: Tue Jan 10 20:52:33 2023 +0800 +| +| rs6000: build constant via li/lis;rldicl/rldicr +| +| If a constant is possible left/right cleaned on a rotated value from +| a negative value of "li/lis". Then, using "li/lis ; rldicl/rldicr" +| to build the constant. The code was doing a -1 << 64 which is undefined behavior because different machines produce different results. On the x86_64 system, (-1 << 64) produces @@ -34,8 +34,12 @@ crosss compiler and on a native PowerPC system. gcc/ PR target/111778 - * config/rs6000/rs6000.cc (can_be_built_by_li_lis_and_rldicl): Do not - use a shift left by the number of bits in a host wide int. + * config/rs6000/rs6000.cc (can_be_built_by_li_lis_and_rldicl): Protect + code from shifts that are undefined. + (can_be_built_by_li_lis_and_rldicr): Likewise. + (can_be_built_by_li_and_rldic): Likewise. + +==================== Branch work139, patch #1 was reverted ==================== ==================== Branch work139, baseline ====================
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