| Message ID | 20240821144817.868AA20432@pchp3.se.axis.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] combine.cc (make_more_copies): Copy attributes from the original pseudo, PR115883 | expand |
On 8/21/24 8:48 AM, Hans-Peter Nilsson wrote: > The only thing that's changed with the patch in v2 since the > first version (pinged once) is the commit message. CC to > the nexts-of-kin as a heads-up. > > Regtested cross to cris-elf and native x86_64-linux-gnu at > r15-3043-g64028d626a50. The gcc.dg/guality/pr54200.c > magically being fixed was also noticed at an earlier > test-run, at r15-1880-gce34fcc572a0. I see on > gcc-testresults that this test fails for several targets. > > Ok to commit? > > -- >8 -- > The first of the late-combine passes, propagates some of the copies > made during the (in-time-)combine pass in make_more_copies into the > users of the "original" pseudo registers and removes the "old" > pseudos. That effectively removes attributes such as REG_POINTER, > which matter to LRA. The quoted PR is for an ICE-manifesting bug that > was exposed by the late-combine pass and went back to hiding with this > patch until commit r15-2937-g3673b7054ec2, the fix for PR116236, when > it was actually fixed. To wit, this patch is only incidentally > related to that bug. > > In other words, the REG_POINTER attribute should not be required for > LRA to work correctly. This patch merely corrects state for those > propagated register-uses to ante late-combine. > > For reasons not investigated, this fixes a failing test > "FAIL: gcc.dg/guality/pr54200.c -Og -DPREVENT_OPTIMIZATION line 20 z == 3" > for x86_64-linux-gnu. > > PR middle-end/115883 > * combine.cc (make_more_copies): Copy attributes from the original > pseudo to the new copy. OK, though please use old fashioned C comment style since that's the style used everywhere else is combine.cc. No need to wait for review on the comment style change ;-) jeff
diff --git a/gcc/combine.cc b/gcc/combine.cc index 3b50bc3529c4..6e6e710aae08 100644 --- a/gcc/combine.cc +++ b/gcc/combine.cc @@ -15102,6 +15102,12 @@ make_more_copies (void) continue; rtx new_reg = gen_reg_rtx (GET_MODE (dest)); + + // The "original" pseudo copies have important attributes + // attached, like pointerness. We want that for these copies + // too, for use by insn recognition and later passes. + set_reg_attrs_from_value (new_reg, dest); + rtx_insn *new_insn = gen_move_insn (new_reg, src); SET_SRC (set) = new_reg; emit_insn_before (new_insn, insn);