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middle-end: Fix up constant handling in emit_conditional_move [PR111260]

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After r14-2667-gceae1400cf24f329393e96dd9720, we force a constant to a register
if it is shared with one of the other operands. The problem is used the comparison
mode for the register but that could be different from the operand mode. This
causes some issues on some targets.
To fix it, we need to make sure the mode of the comparison matches the mode
of the other operands, before we can compare the constants (CONST_INT has no
modes so compare_rtx returns true if they have the same value even if the usage
is in a different mode).

Bootstrapped and tested on both aarch64-linux-gnu and x86_64-linux.

	PR middle-end/111260

gcc/ChangeLog:

	* optabs.cc (emit_conditional_move): Change the modes to be
	equal before forcing the constant to a register.

gcc/testsuite/ChangeLog:

	* gcc.c-torture/compile/condmove-1.c: New test.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
This commit is contained in:
Andrew Pinski 2023-12-12 21:55:50 -08:00
parent 8cccdc2176
commit 5fa27d9f8c
2 changed files with 11 additions and 0 deletions
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2
gcc/optabs.cc
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@ -5131,6 +5131,7 @@ emit_conditional_move (rtx target, struct rtx_comparison comp,
/* If we are optimizing, force expensive constants into a register
but preserve an eventual equality with op2/op3. */
if (CONSTANT_P (orig_op0) && optimize
&& cmpmode == mode
&& (rtx_cost (orig_op0, mode, COMPARE, 0,
optimize_insn_for_speed_p ())
> COSTS_N_INSNS (1))
@ -5142,6 +5143,7 @@ emit_conditional_move (rtx target, struct rtx_comparison comp,
op3p = XEXP (comparison, 0) = force_reg (cmpmode, orig_op0);
}
if (CONSTANT_P (orig_op1) && optimize
&& cmpmode == mode
&& (rtx_cost (orig_op1, mode, COMPARE, 0,
optimize_insn_for_speed_p ())
> COSTS_N_INSNS (1))

9
gcc/testsuite/gcc.c-torture/compile/condmove-1.c Normal file
View file

@ -0,0 +1,9 @@
/* PR middle-end/111260 */
/* Used to ICE while expansion of the `(a == b) ? b : 0;` */
int f1(long long a)
{
int b = 822920;
int t = a == b;
return t * (int)b;
}