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From: Jan Hubicka <hubicka@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-5379] Fix modref wrt __builtin_assume_aligned Date: Thu, 18 Nov 2021 17:42:05 +0000 (GMT) [thread overview] Message-ID: <20211118174205.418363858422@sourceware.org> (raw) https://gcc.gnu.org/g:c331a75d49b6043399f5ccce72a02ccf3b0ddc56 commit r12-5379-gc331a75d49b6043399f5ccce72a02ccf3b0ddc56 Author: Jan Hubicka <jh@suse.cz> Date: Thu Nov 18 18:41:43 2021 +0100 Fix modref wrt __builtin_assume_aligned __builtin_assume_aligned has bit contraictionary fnspec description "1cX " which means that parameter 1 is returned but also unused. PTA code takes precedence to parameter being returned, while modref takes the info that parameter is unused. This patch tweaks modref to follow PTA semantics (as suggested by Richard in the PR log) gcc/ChangeLog: 2021-11-18 Jan Hubicka <hubicka@ucw.cz> PR ipa/103266 * ipa-modref.c (modref_eaf_analysis::merge_call_lhs_flags): Unused parameter may still be returned. (modref_eaf_analysis::analyze_ssa_name): Call merge_call_lhs_flags even for unused function args. gcc/testsuite/ChangeLog: 2021-11-18 Jan Hubicka <hubicka@ucw.cz> PR ipa/103266 * g++.dg/torture/pr103266.C: New test. Diff: --- gcc/ipa-modref.c | 32 ++++++++++++++++++++++---------- gcc/testsuite/g++.dg/torture/pr103266.C | 23 +++++++++++++++++++++++ 2 files changed, 45 insertions(+), 10 deletions(-) diff --git a/gcc/ipa-modref.c b/gcc/ipa-modref.c index c94f0589d44..e5d2b11025a 100644 --- a/gcc/ipa-modref.c +++ b/gcc/ipa-modref.c @@ -2033,10 +2033,7 @@ modref_eaf_analysis::merge_call_lhs_flags (gcall *call, int arg, bool indirect) { int index = SSA_NAME_VERSION (name); - - /* If value is not returned at all, do nothing. */ - if (!direct && !indirect) - return; + bool returned_directly = false; /* If there is no return value, no flags are affected. */ if (!gimple_call_lhs (call)) @@ -2047,10 +2044,23 @@ modref_eaf_analysis::merge_call_lhs_flags (gcall *call, int arg, if (arg >= 0) { int flags = gimple_call_return_flags (call); - if ((flags & ERF_RETURNS_ARG) - && (flags & ERF_RETURN_ARG_MASK) != arg) - return; + if (flags & ERF_RETURNS_ARG) + { + if ((flags & ERF_RETURN_ARG_MASK) == arg) + returned_directly = true; + else + return; + } + } + /* Make ERF_RETURNS_ARG overwrite EAF_UNUSED. */ + if (returned_directly) + { + direct = true; + indirect = false; } + /* If value is not returned at all, do nothing. */ + else if (!direct && !indirect) + return; /* If return value is SSA name determine its flags. */ if (TREE_CODE (gimple_call_lhs (call)) == SSA_NAME) @@ -2273,11 +2283,13 @@ modref_eaf_analysis::analyze_ssa_name (tree name) if (gimple_call_arg (call, i) == name) { int call_flags = gimple_call_arg_flags (call, i); - if (!ignore_retval && !(call_flags & EAF_UNUSED)) + if (!ignore_retval) merge_call_lhs_flags (call, i, name, - !(call_flags & EAF_NOT_RETURNED_DIRECTLY), - !(call_flags & EAF_NOT_RETURNED_INDIRECTLY)); + !(call_flags & (EAF_NOT_RETURNED_DIRECTLY + | EAF_UNUSED)), + !(call_flags & (EAF_NOT_RETURNED_INDIRECTLY + | EAF_UNUSED))); if (!(ecf_flags & (ECF_CONST | ECF_NOVOPS))) { call_flags = callee_to_caller_flags diff --git a/gcc/testsuite/g++.dg/torture/pr103266.C b/gcc/testsuite/g++.dg/torture/pr103266.C new file mode 100644 index 00000000000..d5c13f50979 --- /dev/null +++ b/gcc/testsuite/g++.dg/torture/pr103266.C @@ -0,0 +1,23 @@ +// { dg-do run } +/* { dg-additional-options "-std=c++14" } */ + typedef unsigned int u32; + typedef unsigned char u8; + + static u32 pu8to32(const u8 * p8) __attribute__((noinline)); + static u32 pu8to32(const u8 * p8) { + u32 v; + + __builtin_memcpy(&v, __builtin_assume_aligned(p8, 1), sizeof(u32)); + + return v; + } + + int main(void) { + // dse1 throws this store away + u8 d[sizeof(u32)] = { + 0x07, 0x00, 0x00, 0x07, + }; + + if (pu8to32(d) != 0x07000007) + __builtin_trap(); + }
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