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| author | Jeff Law <jlaw@ventanamicro.com> | 2024-07-21 07:36:37 -0600 |
|---|---|---|
| committer | Thomas Koenig <tkoenig@gcc.gnu.org> | 2024-07-28 19:05:43 +0200 |
| commit | 81e528bfffa44566ca6c93aae4acb407144fd241 (patch) | |
| tree | f7ff97f86202816d129be642104a7a04873b4d7d /gcc | |
| parent | e6431eaa7867b0a55aa3a118ed3f5408f1dd0cbf (diff) | |
| download | gcc-81e528bfffa44566ca6c93aae4acb407144fd241.zip gcc-81e528bfffa44566ca6c93aae4acb407144fd241.tar.gz gcc-81e528bfffa44566ca6c93aae4acb407144fd241.tar.bz2 | |
[PR rtl-optimization/115877] Fix livein computation for ext-dce
So I'm not yet sure how I'm going to break everything down, but this is easy
enough to break out as 1/N of ext-dce fixes/improvements.
When handling uses in an insn, we first determine what bits are set in the
destination which is represented in DST_MASK. Then we use that to refine what
bits are live in the source operands.
In the source operand handling section we *modify* DST_MASK if the source
operand is a SUBREG (ugh!). So if the first operand is a SUBREG, then we can
incorrectly compute which bit groups are live in the second operand, especially
if it is a SUBREG as well.
This was seen when testing a larger set of patches on the rl78 port
(builtin-arith-overflow-p-7 & pr71631 execution failures), so no new test for
this bugfix.
Run through my tester (in conjunction with other ext-dce changes) on the
various cross targets. Run individually through a bootstrap and regression
test cycle on x86_64 as well.
Pushing to the trunk.
PR rtl-optimization/115877
gcc/
* ext-dce.cc (ext_dce_process_uses): Restore the value of DST_MASK
for reach operand.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ext-dce.cc | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/gcc/ext-dce.cc b/gcc/ext-dce.cc index 6d4b885..b4450e4 100644 --- a/gcc/ext-dce.cc +++ b/gcc/ext-dce.cc @@ -591,8 +591,10 @@ ext_dce_process_uses (rtx_insn *insn, rtx obj, bitmap live_tmp) making things live. Breaking from this loop will cause the iterator to work on sub-rtxs, so it is safe to break if we see something we don't know how to handle. */ + unsigned HOST_WIDE_INT save_mask = dst_mask; for (;;) { + dst_mask = save_mask; /* Strip an outer paradoxical subreg. The bits outside the inner mode are don't cares. So we can just strip and process the inner object. */ |