From: Maciej W. Rozycki <macro@embecosm.com>
Date: Wed, 22 Nov 2023 01:18:27 +0000 (+0000)
Subject: RISC-V: Also accept constants for T-Head cond-move data input operands
X-Git-Tag: basepoints/gcc-15~4419
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=566a2b3baa342c7e00b7de7112d92637baba9c75;p=thirdparty%2Fgcc.git

RISC-V: Also accept constants for T-Head cond-move data input operands

There is no need for the requirement for conditional-move data input
operands to be stricter for T-Head targets than for short forward branch
targets and limit them to registers only.  They are keyed according to
the `sfb_alu_operand' predicate, which lets certain constants through.
Such constants are already forced into a register for the `cons' operand
in the analogous short forward branch case and we can force them for the
`alt' operand and T-Head as well.  This enables more opportunities for a
branchless sequence to be produced.

	gcc/
	* config/riscv/riscv.cc (riscv_expand_conditional_move): Also
	accept constants for T-Head data input operands.
---

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index ac2e76f4bedf..cdd1a4f9e254 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -4123,8 +4123,6 @@ riscv_expand_conditional_move (rtx dest, rtx op, rtx cons, rtx alt)
 
   if (TARGET_XTHEADCONDMOV
       && GET_MODE_CLASS (mode) == MODE_INT
-      && reg_or_0_operand (cons, mode)
-      && reg_or_0_operand (alt, mode)
       && (GET_MODE (op) == mode || GET_MODE (op) == E_VOIDmode)
       && (GET_MODE (op0) == mode || CONST_INT_P (op0))
       && (GET_MODE (op1) == mode || CONST_INT_P (op1))
@@ -4142,6 +4140,8 @@ riscv_expand_conditional_move (rtx dest, rtx op, rtx cons, rtx alt)
 	 cases for extensions which are more general than SFB.  But
 	 does mean we need to force CONS into a register at this point.  */
       cons = force_reg (mode, cons);
+      /* With XTheadCondMov we need to force ALT into a register too.  */
+      alt = force_reg (mode, alt);
       emit_insn (gen_rtx_SET (dest, gen_rtx_IF_THEN_ELSE (mode,
 							  cond, cons, alt)));
       return true;