ping
This patch further improves aarch64_legitimate_constant_p. Allow all
integer, floating point and vector constants. Allow label references
and non-anchor symbols with an immediate offset. This allows such
constants to be rematerialized, resulting in smaller code and fewer stack
spills.
SPEC2006 codesize reduces by 0.08%, SPEC2017 by 0.13%.
Bootstrap OK, OK for commit?
ChangeLog:
2017-07-07 Wilco Dijkstra <wdijk...@arm.com>
* config/aarch64/aarch64.c (aarch64_legitimate_constant_p):
Return true for more constants, symbols and label references.
(aarch64_valid_floating_const): Remove unused function.
--
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index
a2eca64a9c13e44d223b5552c079ef4e09659e84..810c17416db01681e99a9eb8cc9f5af137ed2054
100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -10173,49 +10173,46 @@ aarch64_legitimate_pic_operand_p (rtx x)
return true;
}
-/* Return true if X holds either a quarter-precision or
- floating-point +0.0 constant. */
-static bool
-aarch64_valid_floating_const (machine_mode mode, rtx x)
-{
- if (!CONST_DOUBLE_P (x))
- return false;
-
- if (aarch64_float_const_zero_rtx_p (x))
- return true;
-
- /* We only handle moving 0.0 to a TFmode register. */
- if (!(mode == SFmode || mode == DFmode))
- return false;
-
- return aarch64_float_const_representable_p (x);
-}
+/* Implement TARGET_LEGITIMATE_CONSTANT_P hook. Return true for constants
+ that should be rematerialized rather than spilled. */
static bool
aarch64_legitimate_constant_p (machine_mode mode, rtx x)
{
+ /* Support CSE and rematerialization of common constants. */
+ if (CONST_INT_P (x) || CONST_DOUBLE_P (x) || GET_CODE (x) == CONST_VECTOR)
+ return true;
+
/* Do not allow vector struct mode constants. We could support
0 and -1 easily, but they need support in aarch64-simd.md. */
- if (TARGET_SIMD && aarch64_vect_struct_mode_p (mode))
+ if (aarch64_vect_struct_mode_p (mode))
return false;
- /* This could probably go away because
- we now decompose CONST_INTs according to expand_mov_immediate. */
- if ((GET_CODE (x) == CONST_VECTOR
- && aarch64_simd_valid_immediate (x, mode, false, NULL))
- || CONST_INT_P (x) || aarch64_valid_floating_const (mode, x))
- return !targetm.cannot_force_const_mem (mode, x);
+ /* Do not allow wide int constants - this requires support in movti. */
+ if (CONST_WIDE_INT_P (x))
+ return false;
- if (GET_CODE (x) == HIGH
- && aarch64_valid_symref (XEXP (x, 0), GET_MODE (XEXP (x, 0))))
- return true;
+ /* Do not allow const (plus (anchor_symbol, const_int)). */
+ if (GET_CODE (x) == CONST && GET_CODE (XEXP (x, 0)) == PLUS)
+ {
+ x = XEXP (XEXP (x, 0), 0);
+ if (SYMBOL_REF_P (x) && SYMBOL_REF_ANCHOR_P (x))
+ return false;
+ }
+
+ if (GET_CODE (x) == HIGH)
+ x = XEXP (x, 0);
/* Treat symbols as constants. Avoid TLS symbols as they are complex,
so spilling them is better than rematerialization. */
if (SYMBOL_REF_P (x) && !SYMBOL_REF_TLS_MODEL (x))
return true;
- return aarch64_constant_address_p (x);
+ /* Label references are always constant. */
+ if (GET_CODE (x) == LABEL_REF)
+ return true;
+
+ return false;
}
rtx
