Checking in again. Please let me know if there's any other feedback.
> On Apr 24, 2026, at 12:10 AM, Chris Copeland <[email protected]> wrote:
>
> Bumping this with the reviewers of v1 to request any other feedback.
>
> Thanks,
> Chris
>
>> On Apr 15, 2026, at 12:19 AM, Chris Copeland <[email protected]> wrote:
>>
>> v4: Remove ChangeLog edits from the patch.
>>
>> ---
>>
>> Record the presence of asm memory clobbers in ipa_fn_summary and use it
>> in ipa-reference's analyze_function to mark all module statics as read
>> and written. Move pass_ipa_reference before pass_ipa_free_fn_summary so
>> the summary is still available when needed.
>>
>> gcc/ChangeLog:
>>
>> PR ipa/124218
>> * ipa-fnsummary.h (ipa_fn_summary): Add asm_memory_clobber field.
>> * ipa-fnsummary.cc (analyze_function_body): Set asm_memory_clobber
>> when a GIMPLE_ASM with a memory clobber is found.
>> (ipa_merge_fn_summary_after_inlining): Merge asm_memory_clobber.
>> (inline_read_section): Stream in asm_memory_clobber.
>> (ipa_fn_summary_write): Stream out asm_memory_clobber.
>> * ipa-reference.cc (analyze_function): Use asm_memory_clobber from
>> fn summary to mark all module statics as read and written.
>> * passes.def: Move pass_ipa_reference before pass_ipa_free_fn_summary.
>>
>> gcc/testsuite/ChangeLog:
>>
>> PR ipa/124218
>> * gcc.dg/ipa/pr124218.c: New test.
>> * g++.dg/guality/pr55665.C: Remove memory clobber. This memory clobber
>> was being ignored before, and leaving it in now triggers PR124864,
>> breaking the test. Correct PR number in first comment.
>> ---
>> gcc/ipa-fnsummary.cc | 9 ++++++++
>> gcc/ipa-fnsummary.h | 6 +++++-
>> gcc/ipa-reference.cc | 13 +++++++++++
>> gcc/passes.def | 2 +-
>> gcc/testsuite/g++.dg/guality/pr55665.C | 4 ++--
>> gcc/testsuite/gcc.dg/ipa/pr124218.c | 30 ++++++++++++++++++++++++++
>> 6 files changed, 60 insertions(+), 4 deletions(-)
>> create mode 100644 gcc/testsuite/gcc.dg/ipa/pr124218.c
>>
>> diff --git a/gcc/ipa-fnsummary.cc b/gcc/ipa-fnsummary.cc
>> index e187231dfb6..2e1387ec746 100644
>> --- a/gcc/ipa-fnsummary.cc
>> +++ b/gcc/ipa-fnsummary.cc
>> @@ -3200,6 +3200,11 @@ analyze_function_body (struct cgraph_node *node, bool
>> early)
>> }
>> }
>>
>> + if (!info->asm_memory_clobber
>> + && gimple_code (stmt) == GIMPLE_ASM
>> + && gimple_asm_clobbers_memory_p (as_a <gasm *> (stmt)))
>> + info->asm_memory_clobber = true;
>> +
>> /* For target specific information, we want to scan all statements
>> rather than those statements with non-zero weights, to avoid
>> missing to scan something interesting for target information,
>> @@ -4492,6 +4497,7 @@ ipa_merge_fn_summary_after_inlining (struct
>> cgraph_edge *edge)
>> toplev_predicate = true;
>>
>> info->fp_expressions |= callee_info->fp_expressions;
>> + info->asm_memory_clobber |= callee_info->asm_memory_clobber;
>> info->target_info |= callee_info->target_info;
>>
>> if (callee_info->conds)
>> @@ -4838,11 +4844,13 @@ inline_read_section (struct lto_file_decl_data
>> *file_data, const char *data,
>> {
>> info->inlinable = bp_unpack_value (&bp, 1);
>> info->fp_expressions = bp_unpack_value (&bp, 1);
>> + info->asm_memory_clobber = bp_unpack_value (&bp, 1);
>> if (!lto_stream_offload_p)
>> info->target_info = streamer_read_uhwi (&ib);
>> }
>> else
>> {
>> + bp_unpack_value (&bp, 1);
>> bp_unpack_value (&bp, 1);
>> bp_unpack_value (&bp, 1);
>> if (!lto_stream_offload_p)
>> @@ -5084,6 +5092,7 @@ ipa_fn_summary_write (void)
>> bp = bitpack_create (ob->main_stream);
>> bp_pack_value (&bp, info->inlinable, 1);
>> bp_pack_value (&bp, info->fp_expressions, 1);
>> + bp_pack_value (&bp, info->asm_memory_clobber, 1);
>> streamer_write_bitpack (&bp);
>> if (!lto_stream_offload_p)
>> streamer_write_uhwi (ob, info->target_info);
>> diff --git a/gcc/ipa-fnsummary.h b/gcc/ipa-fnsummary.h
>> index de7b7f61cb1..896cb6c1725 100644
>> --- a/gcc/ipa-fnsummary.h
>> +++ b/gcc/ipa-fnsummary.h
>> @@ -126,7 +126,8 @@ public:
>> ipa_fn_summary ()
>> : min_size (0),
>> inlinable (false), single_caller (false),
>> - fp_expressions (false), safe_to_inline_to_always_inline (0),
>> + fp_expressions (false), asm_memory_clobber (false),
>> + safe_to_inline_to_always_inline (0),
>> target_info (0), estimated_stack_size (false),
>> time (0), conds (NULL),
>> size_time_table (), call_size_time_table (vNULL),
>> @@ -141,6 +142,7 @@ public:
>> : min_size (s.min_size),
>> inlinable (s.inlinable), single_caller (s.single_caller),
>> fp_expressions (s.fp_expressions),
>> + asm_memory_clobber (s.asm_memory_clobber),
>> target_info (s.target_info),
>> estimated_stack_size (s.estimated_stack_size),
>> time (s.time), conds (s.conds), size_time_table (),
>> @@ -165,6 +167,8 @@ public:
>> unsigned int single_caller : 1;
>> /* True if function contains any floating point expressions. */
>> unsigned int fp_expressions : 1;
>> + /* True if function contains an asm statement that clobbers memory. */
>> + unsigned int asm_memory_clobber : 1;
>> /* Cache for analysis of can_early_inline_edge_p. */
>> unsigned int safe_to_inline_to_always_inline : 2;
>> /* Like fp_expressions field above, but it's to hold some target specific
>> diff --git a/gcc/ipa-reference.cc b/gcc/ipa-reference.cc
>> index c5699312c8f..12b593b0f50 100644
>> --- a/gcc/ipa-reference.cc
>> +++ b/gcc/ipa-reference.cc
>> @@ -50,6 +50,11 @@ along with GCC; see the file COPYING3. If not see
>> #include "ipa-reference.h"
>> #include "alloc-pool.h"
>> #include "symbol-summary.h"
>> +#include "tree-vrp.h"
>> +#include "sreal.h"
>> +#include "ipa-cp.h"
>> +#include "ipa-prop.h"
>> +#include "ipa-fnsummary.h"
>>
>> /* The static variables defined within the compilation unit that are
>> loaded or stored directly by function that owns this structure. */
>> @@ -507,6 +512,7 @@ analyze_function (struct cgraph_node *fn)
>> {
>> ipa_reference_local_vars_info_t local;
>> struct ipa_ref *ref = NULL;
>> + ipa_fn_summary *sum;
>> int i;
>> tree var;
>>
>> @@ -548,6 +554,13 @@ analyze_function (struct cgraph_node *fn)
>> }
>> }
>>
>> + sum = ipa_fn_summaries->get (fn);
>> + if (sum && sum->asm_memory_clobber)
>> + {
>> + local->statics_read = all_module_statics;
>> + local->statics_written = all_module_statics;
>> + }
>> +
>> if (fn->cannot_return_p ())
>> bitmap_clear (local->statics_written);
>> }
>> diff --git a/gcc/passes.def b/gcc/passes.def
>> index cdddb87302f..8344ea1a584 100644
>> --- a/gcc/passes.def
>> +++ b/gcc/passes.def
>> @@ -176,8 +176,8 @@ along with GCC; see the file COPYING3. If not see
>> NEXT_PASS (pass_ipa_locality_cloning);
>> NEXT_PASS (pass_ipa_pure_const);
>> NEXT_PASS (pass_ipa_modref);
>> - NEXT_PASS (pass_ipa_free_fn_summary, false /* small_p */);
>> NEXT_PASS (pass_ipa_reference);
>> + NEXT_PASS (pass_ipa_free_fn_summary, false /* small_p */);
>> /* This pass needs to be scheduled after any IP code duplication. */
>> NEXT_PASS (pass_ipa_single_use);
>> /* Comdat privatization come last, as direct references to comdat local
>> diff --git a/gcc/testsuite/g++.dg/guality/pr55665.C
>> b/gcc/testsuite/g++.dg/guality/pr55665.C
>> index 16c6d281661..d100d0abc29 100644
>> --- a/gcc/testsuite/g++.dg/guality/pr55665.C
>> +++ b/gcc/testsuite/g++.dg/guality/pr55665.C
>> @@ -1,4 +1,4 @@
>> -// PR debug/55655
>> +// PR debug/55665
>> // { dg-do run }
>> // { dg-options "-g" }
>>
>> @@ -14,7 +14,7 @@ bar (void)
>> __attribute__((noinline, noclone)) void
>> foo (int x)
>> {
>> - __asm volatile ("" : : "r" (x) : "memory");
>> + __asm volatile ("" : : "r" (x));
>> }
>>
>> A::A (int x)
>> diff --git a/gcc/testsuite/gcc.dg/ipa/pr124218.c
>> b/gcc/testsuite/gcc.dg/ipa/pr124218.c
>> new file mode 100644
>> index 00000000000..67e95914d6b
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/ipa/pr124218.c
>> @@ -0,0 +1,30 @@
>> +/* { dg-do run { target arm*-*-eabi* } } */
>> +/* { dg-options "-O1 -fwhole-program" } */
>> +
>> +/* PR ipa/124218: ipa-reference must honor memory clobbers in inline asm.
>> */
>> +
>> +int flag;
>> +
>> +__attribute__ ((used))
>> +void
>> +asm_set (void)
>> +{
>> + flag = 1;
>> +}
>> +
>> +__attribute__ ((noinline))
>> +static void
>> +clobber_and_set (void)
>> +{
>> + __asm__ volatile ("bl asm_set" ::: "r0", "r1", "r2", "r3",
>> + "ip", "lr", "memory", "cc");
>> +}
>> +
>> +int main (void)
>> +{
>> + flag = 0;
>> + clobber_and_set ();
>> + if (!flag)
>> + __builtin_abort ();
>> + return 0;
>> +}
>> --
>> 2.53.0
>>
>
