[PATCH] Replace a HWI_COMPUTABLE_MODE_P with wide-int in simplify-rtx.cc.

[Roger Sayle]

This patch enhances one of the optimizations in simplify_binary_operation_1
to allow it to simplify RTL expressions in modes than HOST_WIDE_INT by
replacing a use of HWI_COMPUTABLE_MODE_P and UINTVAL with wide_int.

The motivating example is a pending x86_64 backend patch that produces
the following RTL in combine:

(and:TI (zero_extend:TI (reg:DI 89))
        (const_wide_int 0x0ffffffffffffffff))

where the AND is redundant, as the mask, ~0LL, is DImode's MODE_MASK.
There's already an optimization that catches this for narrower modes,
transforming (and:HI (zero_extend:HI (reg:QI x)) (const_int 0xff))
into (zero_extend:HI (reg:QI x)), but this currently only handles
CONST_INT not CONST_WIDE_INT.  Fixed by upgrading this transformation
to use wide_int, specifically rtx_mode_t and wi::mask.

This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
and make -k check, both with and without --target_board=unix{-m32}
with no new failures.  Ok for mainline?


2023-05-23  Roger Sayle  <ro...@nextmovesoftware.com>

gcc/ChangeLog
        * simplify-rtx.cc (simplify_binary_operation_1) <AND>: Use wide-int
        instead of HWI_COMPUTABLE_MODE_P and UINTVAL in transformation of
        (and (extend X) C) as (zero_extend (and X C)), to also optimize
        modes wider than HOST_WIDE_INT.


Thanks in advance,
Roger
--


diff --git a/gcc/simplify-rtx.cc b/gcc/simplify-rtx.cc
index d4aeebc..8dc880b 100644
--- a/gcc/simplify-rtx.cc
+++ b/gcc/simplify-rtx.cc
@@ -3826,15 +3826,16 @@ simplify_context::simplify_binary_operation_1 (rtx_code 
code,
         there are no nonzero bits of C outside of X's mode.  */
       if ((GET_CODE (op0) == SIGN_EXTEND
           || GET_CODE (op0) == ZERO_EXTEND)
-         && CONST_INT_P (trueop1)
-         && HWI_COMPUTABLE_MODE_P (mode)
-         && (~GET_MODE_MASK (GET_MODE (XEXP (op0, 0)))
-             & UINTVAL (trueop1)) == 0)
+         && CONST_SCALAR_INT_P (trueop1)
+         && is_a <scalar_int_mode> (mode, &int_mode)
+         && is_a <scalar_int_mode> (GET_MODE (XEXP (op0, 0)), &inner_mode)
+         && (wi::mask (GET_MODE_PRECISION (inner_mode), true,
+                       GET_MODE_PRECISION (int_mode))
+             & rtx_mode_t (trueop1, mode)) == 0)
        {
          machine_mode imode = GET_MODE (XEXP (op0, 0));
-         tem = simplify_gen_binary (AND, imode, XEXP (op0, 0),
-                                    gen_int_mode (INTVAL (trueop1),
-                                                  imode));
+         tem = immed_wide_int_const (rtx_mode_t (trueop1, mode), imode);
+         tem = simplify_gen_binary (AND, imode, XEXP (op0, 0), tem);
          return simplify_gen_unary (ZERO_EXTEND, mode, tem, imode);
        }