Avoid going through another folding cycle and use the ignore flag to directly transform BUILT_IN_STPCPY_CHK to BUILT_IN_STRCPY when set, likewise for BUILT_IN_STPNCPY_CHK to BUILT_IN_STPNCPY.
Dump the transformation in dump_file so that we can verify in tests that the direct transformation actually happened. 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. gcc/testsuite/ChangeLog: * gcc.dg/fold-stringops.c: New test. Signed-off-by: Siddhesh Poyarekar <siddh...@gotplt.org> --- gcc/gimple-fold.c | 50 +++++++++++++++++-------- gcc/testsuite/gcc.dg/fold-stringops-1.c | 23 ++++++++++++ 2 files changed, 57 insertions(+), 16 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/fold-stringops-1.c diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c index 6e25a7c05db..92e15784803 100644 --- a/gcc/gimple-fold.c +++ b/gcc/gimple-fold.c @@ -3088,6 +3088,19 @@ gimple_fold_builtin_memory_chk (gimple_stmt_iterator *gsi, return true; } +static void +dump_transformation (gimple *from, gimple *to) +{ + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "transformed "); + print_generic_expr (dump_file, gimple_call_fn (from), dump_flags); + fprintf (dump_file, " to "); + print_generic_expr (dump_file, gimple_call_fn (to), dump_flags); + fprintf (dump_file, "\n"); + } +} + /* Fold a call to the __st[rp]cpy_chk builtin. DEST, SRC, and SIZE are the arguments to the call. IGNORE is true if return value can be ignored. FCODE is the BUILT_IN_* @@ -3184,12 +3197,13 @@ 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; gimple *repl = gimple_build_call (fn, 2, dest, src); + dump_transformation (stmt, repl); replace_call_with_call_and_fold (gsi, repl); return true; } @@ -3209,19 +3223,6 @@ gimple_fold_builtin_stxncpy_chk (gimple_stmt_iterator *gsi, bool ignore = gimple_call_lhs (stmt) == NULL_TREE; tree fn; - if (fcode == BUILT_IN_STPNCPY_CHK && ignore) - { - /* If return value of __stpncpy_chk is ignored, - optimize into __strncpy_chk. */ - fn = builtin_decl_explicit (BUILT_IN_STRNCPY_CHK); - if (fn) - { - gimple *repl = gimple_build_call (fn, 4, dest, src, len, size); - replace_call_with_call_and_fold (gsi, repl); - return true; - } - } - if (! tree_fits_uhwi_p (size)) return false; @@ -3234,7 +3235,23 @@ gimple_fold_builtin_stxncpy_chk (gimple_stmt_iterator *gsi, For MAXLEN only allow optimizing into non-_ocs function if SIZE is >= MAXLEN, never convert to __ocs_fail (). */ if (maxlen == NULL_TREE || ! tree_fits_uhwi_p (maxlen)) - return false; + { + if (fcode == BUILT_IN_STPNCPY_CHK && ignore) + { + /* If return value of __stpncpy_chk is ignored, + optimize into __strncpy_chk. */ + fn = builtin_decl_explicit (BUILT_IN_STRNCPY_CHK); + if (fn) + { + gimple *repl = gimple_build_call (fn, 4, dest, src, len, + size); + replace_call_with_call_and_fold (gsi, repl); + return true; + } + } + + return false; + } } else maxlen = len; @@ -3244,12 +3261,13 @@ gimple_fold_builtin_stxncpy_chk (gimple_stmt_iterator *gsi, } /* 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; gimple *repl = gimple_build_call (fn, 3, dest, src, len); + dump_transformation (stmt, repl); replace_call_with_call_and_fold (gsi, repl); return true; } diff --git a/gcc/testsuite/gcc.dg/fold-stringops-1.c b/gcc/testsuite/gcc.dg/fold-stringops-1.c new file mode 100644 index 00000000000..712dd369e7c --- /dev/null +++ b/gcc/testsuite/gcc.dg/fold-stringops-1.c @@ -0,0 +1,23 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-lower-details" } */ + +char dst[2048]; + +char * +copy1 (const char *src, int cond) +{ + __builtin___stpncpy_chk (dst, src, 42, __builtin_object_size (dst, 0)); + + return dst; +} + +char * +copy2 (void) +{ + __builtin___stpcpy_chk (dst, "Hello world", __builtin_object_size (dst, 0)); + + return dst; +} +/* { dg-final { scan-tree-dump "transformed __builtin___stpncpy_chk to __builtin_strncpy" "lower" } } */ +/* { dg-final { scan-tree-dump "transformed __builtin___stpcpy_chk to __builtin_strcpy" "lower" } } */ + -- 2.31.1