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tree-optimization/108691 - indirect calls to setjmp

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DCE now chokes on indirect setjmp calls becoming direct because
that exposes them too late to be subject to abnormal edge creation.
The following patch honors gimple_call_ctrl_altering for those and
_not_ treat formerly indirect calls to setjmp as calls to setjmp
in notice_special_calls.

Unfortunately there's no way to have an indirect call to setjmp
properly annotated (the returns_twice attribute is ignored on types).

RTL expansion late discovers returns-twice for the purpose of
adding REG_SETJMP notes and also sets ->calls_setjmp
(instead of asserting it is set).  There's no good way to
transfer proper knowledge around here so I'm using ->calls_setjmp
as a flag to indicate whether gimple_call_ctrl_altering_p was set.

	PR tree-optimization/108691
	* tree-cfg.cc (notice_special_calls): When the CFG is built
	honor gimple_call_ctrl_altering_p.
	* cfgexpand.cc (expand_call_stmt): Clear cfun->calls_setjmp
	temporarily if the call is not control-altering.
	* calls.cc (emit_call_1): Do not add REG_SETJMP if
	cfun->calls_setjmp is not set.  Do not alter cfun->calls_setjmp.

	* gcc.dg/pr108691.c: New testcase.
This commit is contained in:
Richard Biener 2023-02-13 10:41:51 +01:00
parent 452db716d8
commit 6436add49e
4 changed files with 24 additions and 6 deletions
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10
gcc/calls.cc
View file

@ -506,11 +506,11 @@ emit_call_1 (rtx funexp, tree fntree ATTRIBUTE_UNUSED, tree fndecl ATTRIBUTE_UNU
if (ecf_flags & ECF_NORETURN)
add_reg_note (call_insn, REG_NORETURN, const0_rtx);
if (ecf_flags & ECF_RETURNS_TWICE)
{
add_reg_note (call_insn, REG_SETJMP, const0_rtx);
cfun->calls_setjmp = 1;
}
if (ecf_flags & ECF_RETURNS_TWICE
/* We rely on GIMPLE setting this flag and here use it to
catch formerly indirect and not control-altering calls. */
&& cfun->calls_setjmp)
add_reg_note (call_insn, REG_SETJMP, const0_rtx);
SIBLING_CALL_P (call_insn) = ((ecf_flags & ECF_SIBCALL) != 0);

7
gcc/cfgexpand.cc
View file

@ -2808,6 +2808,11 @@ expand_call_stmt (gcall *stmt)
/* Must come after copying location. */
copy_warning (exp, stmt);
/* For calls that do not alter control flow avoid REG_SETJMP notes. */
bool saved_calls_setjmp = cfun->calls_setjmp;
if (!gimple_call_ctrl_altering_p (stmt))
cfun->calls_setjmp = false;
/* Ensure RTL is created for debug args. */
if (decl && DECL_HAS_DEBUG_ARGS_P (decl))
{
@ -2846,6 +2851,8 @@ expand_call_stmt (gcall *stmt)
}
mark_transaction_restart_calls (stmt);
cfun->calls_setjmp = saved_calls_setjmp;
}

9
gcc/testsuite/gcc.dg/pr108691.c Normal file
View file

@ -0,0 +1,9 @@
/* { dg-do compile } */
/* { dg-options "-O2" } */
extern int __attribute__((returns_twice)) setjmp(void*);
void bbb(void) {
int (*fnptr)(void*) = setjmp;
fnptr(0);
}

4
gcc/tree-cfg.cc
View file

@ -2280,7 +2280,9 @@ notice_special_calls (gcall *call)
if (flags & ECF_MAY_BE_ALLOCA)
cfun->calls_alloca = true;
if (flags & ECF_RETURNS_TWICE)
if (flags & ECF_RETURNS_TWICE
&& (!(cfun->curr_properties & PROP_cfg)
|| gimple_call_ctrl_altering_p (call)))
cfun->calls_setjmp = true;
}