From 7950c96ca667ddaab9d6e894da3958ebc2e2dccb Mon Sep 17 00:00:00 2001 From: Jeff Law Date: Sat, 20 Nov 2021 11:20:07 -0500 Subject: [PATCH] Clobber the condition code in the bfin doloop patterns Per Aldy's excellent, but tough to follow analysis in PR 103226, this patch fixes the bfin-elf regression. In simplest terms the doloop patterns on this port may clobber the condition code register, but they do not expose that until after register allocation. That would be fine, except that other patterns have exposed CC earlier. As a result the dataflow, particularly for CC, is incorrect. This leads the register allocators to assume that a value in CC outside the loop is still valid inside the loop when in fact, the value has been clobbered. This is what caused pr80974 to start failing. With this fix, not only do we fix the pr80974 regression, but we fix ~20 other execution failures in the port. It also reduces test time for the port from ~90 minutes to ~60 minutes. PR tree-optimization/103226 gcc/ * config/bfin/bfin.md (doloop pattern, splitter and expander): Clobber CC. --- gcc/config/bfin/bfin.md | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/gcc/config/bfin/bfin.md b/gcc/config/bfin/bfin.md index fd65f4d9e63..10a19aac23e 100644 --- a/gcc/config/bfin/bfin.md +++ b/gcc/config/bfin/bfin.md @@ -1959,7 +1959,8 @@ (plus:SI (match_dup 0) (const_int -1))) (unspec [(const_int 0)] UNSPEC_LSETUP_END) - (clobber (match_dup 2))])] ; match_scratch + (clobber (match_dup 2)) + (clobber (reg:BI REG_CC))])] ; match_scratch "" { /* The loop optimizer doesn't check the predicates... */ @@ -1979,7 +1980,8 @@ (plus (match_dup 2) (const_int -1))) (unspec [(const_int 0)] UNSPEC_LSETUP_END) - (clobber (match_scratch:SI 3 "=X,&r,&r"))] + (clobber (match_scratch:SI 3 "=X,&r,&r")) + (clobber (reg:BI REG_CC))] "" "@ /* loop end %0 %l1 */ @@ -1997,7 +1999,8 @@ (plus (match_dup 0) (const_int -1))) (unspec [(const_int 0)] UNSPEC_LSETUP_END) - (clobber (match_scratch:SI 2))] + (clobber (match_scratch:SI 2)) + (clobber (reg:BI REG_CC))] "memory_operand (operands[0], SImode) || splitting_loops" [(set (match_dup 2) (match_dup 0)) (set (match_dup 2) (plus:SI (match_dup 2) (const_int -1)))