https://gcc.gnu.org/g:966cdec2b23b8049c263e2239a3da38937ae01d2
commit r16-4081-g966cdec2b23b8049c263e2239a3da38937ae01d2 Author: Andrew Pinski <[email protected]> Date: Fri Sep 19 20:58:31 2025 -0700 gimple-fold/fab: Move ASSUME_ALIGNED handling to gimple-fold [PR121762] This is the next patch in the series of removing fab. This one is simplier than builtin_constant_p because the only time we want to simplify this builtin is at the final folding step. Note align-5.c needs to change slightly as __builtin_assume_aligned is no longer taken into account for the same reason as why PR 111875 is closed as invalid and why the testcase is failing at -Og I added a new testcase align-5a.c where the pointer is explictly aligned so that the check is gone there. Note __builtin_assume_aligned should really be instrumented for UBSAN, I filed PR 122038 for that. Bootstrapped and tested on x86_64-linux-gnu. PR tree-optimization/121762 gcc/ChangeLog: * gimple-fold.cc (gimple_fold_builtin_assume_aligned): New function. (gimple_fold_builtin): Call gimple_fold_builtin_assume_aligned for BUILT_IN_ASSUME_ALIGNED. * tree-ssa-ccp.cc (pass_fold_builtins::execute): Remove handling of BUILT_IN_ASSUME_ALIGNED. gcc/testsuite/ChangeLog: * c-c++-common/ubsan/align-5.c: Update as __builtin_assume_aligned is no longer taked into account. * c-c++-common/ubsan/align-5a.c: New test. Signed-off-by: Andrew Pinski <[email protected]> Diff: --- gcc/gimple-fold.cc | 21 +++++++++++++++++++++ gcc/testsuite/c-c++-common/ubsan/align-5.c | 7 +++---- gcc/testsuite/c-c++-common/ubsan/align-5a.c | 18 ++++++++++++++++++ gcc/tree-ssa-ccp.cc | 5 ----- 4 files changed, 42 insertions(+), 9 deletions(-) diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc index 229b1b301a4f..37ca0853ec82 100644 --- a/gcc/gimple-fold.cc +++ b/gcc/gimple-fold.cc @@ -5234,6 +5234,24 @@ gimple_fold_builtin_constant_p (gimple_stmt_iterator *gsi) return true; } +/* Fold __builtin_assume_aligned builtin. */ + +static bool +gimple_fold_builtin_assume_aligned (gimple_stmt_iterator *gsi) +{ + if (!(cfun->curr_properties & PROP_last_full_fold)) + return false; + + gcall *call = as_a<gcall*>(gsi_stmt (*gsi)); + + if (gimple_call_num_args (call) < 2) + return false; + + gimplify_and_update_call_from_tree (gsi, gimple_call_arg (call, 0)); + + return true; +} + /* Fold the non-target builtin at *GSI and return whether any simplification was made. */ @@ -5406,6 +5424,9 @@ gimple_fold_builtin (gimple_stmt_iterator *gsi) case BUILT_IN_CONSTANT_P: return gimple_fold_builtin_constant_p (gsi); + case BUILT_IN_ASSUME_ALIGNED: + return gimple_fold_builtin_assume_aligned (gsi); + default:; } diff --git a/gcc/testsuite/c-c++-common/ubsan/align-5.c b/gcc/testsuite/c-c++-common/ubsan/align-5.c index b94e167bb67b..484790134a66 100644 --- a/gcc/testsuite/c-c++-common/ubsan/align-5.c +++ b/gcc/testsuite/c-c++-common/ubsan/align-5.c @@ -1,8 +1,7 @@ /* { dg-do compile } */ /* { dg-options "-fno-sanitize=null -fsanitize=alignment -O2" } */ -/* Check that when optimizing if we know the alignment is right - and we are not doing -fsanitize=null instrumentation we don't - instrument the alignment check. */ +/* __builtin_assume_aligned should be instrumented too. UBSAN alignment + should not depend on it. */ __attribute__((noinline, noclone)) int foo (char *p) @@ -12,4 +11,4 @@ foo (char *p) return *q; } -/* { dg-final { scan-assembler-not "__ubsan_handle" } } */ +/* { dg-final { scan-assembler "__ubsan_handle" } } */ diff --git a/gcc/testsuite/c-c++-common/ubsan/align-5a.c b/gcc/testsuite/c-c++-common/ubsan/align-5a.c new file mode 100644 index 000000000000..d86e5377e033 --- /dev/null +++ b/gcc/testsuite/c-c++-common/ubsan/align-5a.c @@ -0,0 +1,18 @@ +/* { dg-do compile } */ +/* { dg-options "-fno-sanitize=null -fsanitize=alignment -O2" } */ +/* Check that when optimizing if we know the alignment is right + and we are not doing -fsanitize=null instrumentation we don't + instrument the alignment check. */ + +__attribute__((noinline, noclone)) int +foo (int *p) +{ + /* Align the pointer explictly. */ + __INTPTR_TYPE__ t = (__INTPTR_TYPE__)p; + t &= ~0xf; + p = (int*)t; + + return *p; +} + +/* { dg-final { scan-assembler-not "__ubsan_handle" } } */ diff --git a/gcc/tree-ssa-ccp.cc b/gcc/tree-ssa-ccp.cc index c74f7cc9d0c5..4165e596033f 100644 --- a/gcc/tree-ssa-ccp.cc +++ b/gcc/tree-ssa-ccp.cc @@ -4284,11 +4284,6 @@ pass_fold_builtins::execute (function *fun) switch (DECL_FUNCTION_CODE (callee)) { - case BUILT_IN_ASSUME_ALIGNED: - /* Remove __builtin_assume_aligned. */ - result = gimple_call_arg (stmt, 0); - break; - case BUILT_IN_STACK_RESTORE: result = optimize_stack_restore (i); if (result)
