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aarch64: Tweak post-RA handling of CONST_INT moves [PR98136]

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This PR is a regression caused by r8-5967, where we replaced
a call to aarch64_internal_mov_immediate in aarch64_add_offset
with a call to aarch64_force_temporary, which in turn uses the
normal emit_move_insn{,_1} routines.

The problem is that aarch64_add_offset can be called while
outputting a thunk, where we require all instructions to be
valid without splitting.  However, the move expanders were
not splitting CONST_INT moves themselves.

I think the right fix is to make the move expanders work
even in this scenario, rather than require callers to handle
it as a special case.

gcc/
	PR target/98136
	* config/aarch64/aarch64.md (mov<mode>): Pass multi-instruction
	CONST_INTs to aarch64_expand_mov_immediate when called after RA.

gcc/testsuite/
	PR target/98136
	* g++.dg/pr98136.C: New test.
This commit is contained in:
Richard Sandiford 2021-03-30 11:42:50 +01:00
parent cc2fda1328
commit 48c79f054b
2 changed files with 39 additions and 4 deletions
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17
gcc/config/aarch64/aarch64.md
View File

@ -1241,10 +1241,19 @@
if (GET_CODE (operands[0]) == MEM && operands[1] != const0_rtx)
operands[1] = force_reg (<MODE>mode, operands[1]);
/* FIXME: RR we still need to fix up what we are doing with
symbol_refs and other types of constants. */
if (CONSTANT_P (operands[1])
&& !CONST_INT_P (operands[1]))
/* Lower moves of symbolic constants into individual instructions.
Doing this now is sometimes necessary for correctness, since some
sequences require temporary pseudo registers. Lowering now is also
often better for optimization, since more RTL passes get the
chance to optimize the individual instructions.
When called after RA, also split multi-instruction moves into
smaller pieces now, since we can't be sure that sure that there
will be a following split pass. */
if (CONST_INT_P (operands[1])
? (reload_completed
&& !aarch64_mov_imm_operand (operands[1], <MODE>mode))
: CONSTANT_P (operands[1]))
{
aarch64_expand_mov_immediate (operands[0], operands[1]);
DONE;

26
gcc/testsuite/g++.dg/pr98136.C Normal file
View File

@ -0,0 +1,26 @@
// { dg-do compile { target { ilp32 || lp64 } } }
struct AddIn
{
virtual ~AddIn() {}
virtual void AddInCall()=0;
};
struct Base
{
char b[32*1024*1024]; // Anything bigger than 16mb causes internal compiler error
virtual ~Base() {}
};
struct Deriv : public Base,
public AddIn
{
void AddInCall() {}
};
int main (int argc, char **argv)
{
Deriv deriv;
deriv.AddInCall();
return 0;
}