rvp: refine the sign-extension and extration of mulplication result

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>

riscv/insns/mqrwacc.h

@@ -1,3 +1,4 @@
 require_extension('P');
 require_rv32;
-WRITE_P_RD_PAIR(P_RD_PAIR + (((sreg_t)RS1*(sreg_t)RS2 + 0x40000000) >> 31));
+int64_t tmp = (((int128_t)(int32_t)RS1 * (int32_t)RS2) + (1 << 30)) >> 31;
+WRITE_P_RD_PAIR(P_RD_PAIR + tmp);

riscv/insns/mqwacc.h

@@ -1,3 +1,4 @@
 require_extension('P');
 require_rv32;
-WRITE_P_RD_PAIR(P_RD_PAIR + (((sreg_t)RS1*(sreg_t)RS2) >> 31));
+int64_t tmp = (((int128_t)(int32_t)RS1 * (int32_t)RS2)) >> 31;
+WRITE_P_RD_PAIR((P_RD_PAIR + tmp));

riscv/insns/pmqrwacc_h.h

@@ -1,4 +1,5 @@
 require_rv32;
 P_WIDEN_RD_RS1_RS2_LOOP(16, 16, {
-  p_rd += (p_rs1 * p_rs2 + 0x4000) >> 15;
+  int64_t val = ((int64_t)(int16_t)p_rs1 * (int64_t)(int16_t)p_rs2 + 0x4000) >> 15;
-})
+  p_rd += val;
+})

riscv/insns/pmqwacc_h.h

@@ -1,4 +1,5 @@
 require_rv32;
 P_WIDEN_RD_RS1_RS2_LOOP(16, 16, {
-  p_rd += (p_rs1 * p_rs2) >> 15;
+  int64_t val = ((int64_t)(int16_t)p_rs1 * (int64_t)(int16_t)p_rs2) >> 15;
-})
+  p_rd += val;
+})