| Message ID | 20211110174728.3932930-1-siddhesh@gotplt.org |
|---|---|
| State | New |
| Headers | show |
| Series | gimple-fold: Transform stp*cpy_chk to strcpy | expand |
On 11/10/2021 10:47 AM, Siddhesh Poyarekar wrote: > Use the ignore flag to transform BUILT_IN_STPCPY_CHK to BUILT_IN_STRCPY > when set. This transformation will happen in a subsequent fold anyway > but do it right away and save the additional effort. > > gcc/ChangeLog: > > * gimple-fold.c (gimple_fold_builtin_stxcpy_chk, > gimple_fold_builtin_stxncpy_chk): Use BUILT_IN_STRNCPY if return > value is not used. OK. Note we usually want testcases for this kind of stuff too. It's not strictly necessary, but it's hard to go wrong if you're including a test that verifies your transformation happens at the point where you expect it to happen. Jeff
On 11/11/21 02:06, Jeff Law wrote: > > > On 11/10/2021 10:47 AM, Siddhesh Poyarekar wrote: >> Use the ignore flag to transform BUILT_IN_STPCPY_CHK to BUILT_IN_STRCPY >> when set. This transformation will happen in a subsequent fold anyway >> but do it right away and save the additional effort. >> >> gcc/ChangeLog: >> >> * gimple-fold.c (gimple_fold_builtin_stxcpy_chk, >> gimple_fold_builtin_stxncpy_chk): Use BUILT_IN_STRNCPY if return >> value is not used. > OK. > > Note we usually want testcases for this kind of stuff too. It's not > strictly necessary, but it's hard to go wrong if you're including a test > that verifies your transformation happens at the point where you expect > it to happen. I started looking at how I would write a test for this since the folder would recursively simplify the statement in the same pass and realized that the transformation sequence during lowering is __stpncpy_chk -> __strncpy_chk -> __strncpy. As a result the transformation I'm trying to do already will have happened higher up. I'm testing an updated patch that avoids having to fold twice and go directly from __stpncpy_chk -> __strncpy. Siddhesh
diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c index 74c9ce4bdc8..cadccfe3010 100644 --- a/gcc/gimple-fold.c +++ b/gcc/gimple-fold.c @@ -3176,7 +3176,7 @@ gimple_fold_builtin_stxcpy_chk (gimple_stmt_iterator *gsi, } /* If __builtin_st{r,p}cpy_chk is used, assume st{r,p}cpy is available. */ - fn = builtin_decl_explicit (fcode == BUILT_IN_STPCPY_CHK + fn = builtin_decl_explicit (fcode == BUILT_IN_STPCPY_CHK && !ignore ? BUILT_IN_STPCPY : BUILT_IN_STRCPY); if (!fn) return false; @@ -3220,7 +3220,7 @@ gimple_fold_builtin_stxncpy_chk (gimple_stmt_iterator *gsi, return false; /* If __builtin_st{r,p}ncpy_chk is used, assume st{r,p}ncpy is available. */ - fn = builtin_decl_explicit (fcode == BUILT_IN_STPNCPY_CHK + fn = builtin_decl_explicit (fcode == BUILT_IN_STPNCPY_CHK && !ignore ? BUILT_IN_STPNCPY : BUILT_IN_STRNCPY); if (!fn) return false;
Use the ignore flag to transform BUILT_IN_STPCPY_CHK to BUILT_IN_STRCPY when set. This transformation will happen in a subsequent fold anyway but do it right away and save the additional effort. gcc/ChangeLog: * gimple-fold.c (gimple_fold_builtin_stxcpy_chk, gimple_fold_builtin_stxncpy_chk): Use BUILT_IN_STRNCPY if return value is not used. Signed-off-by: Siddhesh Poyarekar <siddhesh@gotplt.org> --- gcc/gimple-fold.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)