RISC-V: fix TARGET_PROMOTE_FUNCTION_MODE hook for libcalls

Fixes: 3496ca4e6566 ("RISC-V: Add runtime invariant support")
riscv_promote_function_mode doesn't promote a SI to DI for libcalls
case. It intends to do that however the code is broken (regression).

The fix is what generic promote_mode () in explow.cc does. I really
don't understand why the old code didn't work, but stepping thru the
debugger shows old code didn't and fixed does.

This showed up when testing Ajit's REE ABI extension series which probes
the ABI (using a NULL tree type) and ends up hitting the libcall code path.

gcc/ChangeLog:
	* config/riscv/riscv.cc (riscv_promote_function_mode): Fix mode
	returned for libcall case.

Tested-by: Patrick O'Neill <patrick@rivosinc.com> # pre-commit-CI #526
Signed-off-by: Vineet Gupta <vineetg@rivosinc.com>

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 0148a4f2e431457e595ffddbfa2c66eb58a42000..895a098cd9a6258624433d6545f0e044d5083fe9 100644 (file)
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -8630,9 +8630,10 @@ riscv_promote_function_mode (const_tree type ATTRIBUTE_UNUSED,
     return promote_mode (type, mode, punsignedp);
 
   unsignedp = *punsignedp;
-  PROMOTE_MODE (as_a <scalar_mode> (mode), unsignedp, type);
+  scalar_mode smode = as_a <scalar_mode> (mode);
+  PROMOTE_MODE (smode, unsignedp, type);
   *punsignedp = unsignedp;
-  return mode;
+  return smode;
 }
 
 /* Implement TARGET_MACHINE_DEPENDENT_REORG.  */