[committed] [PR target/109508] Adjust conditional move expansion for SFB

Recently the conditional move expander's predicates were loosened for the
benefit of the THEAD processors.  In particular one operand that was
previously "register_operand" is now "reg_or_0_operand".  That's fine for
THEAD, but breaks for SFB which requires a register for that operand.

This results in an ICE when compiling the testcase an SFB target such as
the sifive s76.

This change adjusts the expansion code slightly to copy the value into
a register for SFB.

Bootstrapped and regression tested (c,c++,fortran only) with a toolchain
configured to enable SFB by default.

	PR target/109508
gcc/

	* config/riscv/riscv.cc (riscv_expand_conditional_move): For
	TARGET_SFB_ALU, force the true arm into a register.

gcc/testsuite
	* gcc.target/riscv/pr109508.c: New test.

2 files changed, 18 insertions, 0 deletions

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index dc47434fac4..e88fa2d6337 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -3419,6 +3419,12 @@ riscv_expand_conditional_move (rtx dest, rtx op, rtx cons, rtx alt)
     {
       riscv_emit_int_compare (&code, &op0, &op1);
       rtx cond = gen_rtx_fmt_ee (code, GET_MODE (op0), op0, op1);
+
+      /* The expander allows (const_int 0) for CONS for the benefit of
+	 TARGET_XTHEADCONDMOV, but that case isn't supported for
+	 TARGET_SFB_ALU.  So force that operand into a register if
+	 necessary.  */
+      cons = force_reg (GET_MODE (dest), cons);
       emit_insn (gen_rtx_SET (dest, gen_rtx_IF_THEN_ELSE (GET_MODE (dest),
 							  cond, cons, alt)));
       return true;
diff --git a/gcc/testsuite/gcc.target/riscv/pr109508.c b/gcc/testsuite/gcc.target/riscv/pr109508.c
new file mode 100644
index 00000000000..65f291e17ed
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/pr109508.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-mcpu=sifive-s76" } */
+
+typedef char __attribute__((__vector_size__ (1))) V;
+
+V v;
+
+void
+foo (void)
+{
+  (char) __builtin_shuffle (0 % v, (V){6}, v);
+}