[1/3] gimple-fold: Transform stp*cpy_chk to str*cpy directly
Commit Message
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 <siddhesh@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
Comments
On Fri, 12 Nov 2021 at 01:12, Siddhesh Poyarekar <siddhesh@gotplt.org> wrote:
>
> 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 <siddhesh@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)
I assume that both from and to will always be builtin calls ?
In that case, perhaps better to use gcall * here (and in rest of patch).
Also, needs a top-level comment describing the function.
> +{
> + if (dump_file && (dump_flags & TDF_DETAILS))
Perhaps better to use dump_enabled_p ?
> + {
> + fprintf (dump_file, "transformed ");
Perhaps use dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, ...) ?
I think you can use gimple_location to get the location.
Thanks,
Prathamesh
> + 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
>
On 11/12/21 22:46, Prathamesh Kulkarni wrote:
> On Fri, 12 Nov 2021 at 01:12, Siddhesh Poyarekar <siddhesh@gotplt.org> wrote:
>>
>> 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 <siddhesh@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)
> I assume that both from and to will always be builtin calls ?
> In that case, perhaps better to use gcall * here (and in rest of patch).
> Also, needs a top-level comment describing the function.
>> +{
>> + if (dump_file && (dump_flags & TDF_DETAILS))
> Perhaps better to use dump_enabled_p ?
>> + {
>> + fprintf (dump_file, "transformed ");
> Perhaps use dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, ...) ?
> I think you can use gimple_location to get the location.
>
Thanks, I'll fix these up.
Siddhesh
@@ -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;
}
new file mode 100644
@@ -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" } } */
+