diff mbox series

[2/2] sim: riscv: Simplify the signed div by -1 code

Message ID AS8P193MB12858E260739E6109ED66D4EE4092@AS8P193MB1285.EURP193.PROD.OUTLOOK.COM
State New
Headers
Series [1/2] sim: riscv: fix a divw division by -1 bug |

Checks

Context Check Description
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linaro-tcwg-bot/tcwg_gdb_build--master-arm success Testing passed
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linaro-tcwg-bot/tcwg_gdb_check--master-aarch64 success Testing passed

Commit Message

Bernd Edlinger April 15, 2024, 2:46 p.m. UTC 
  This uses the idea from the previous patch to
simplify the code for non-overflowing signed
divisions by -1.  This is no bug-fix but it
simplifies the code and avoids some unnecessary
branches.
---
 sim/riscv/sim-main.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/sim/riscv/sim-main.c b/sim/riscv/sim-main.c
index 515ff835223..e4b15b533ba 100644
--- a/sim/riscv/sim-main.c
+++ b/sim/riscv/sim-main.c
@@ -700,18 +700,16 @@  execute_m (SIM_CPU *cpu, unsigned_word iw, const struct riscv_opcode *op)
   const char *rd_name = riscv_gpr_names_abi[rd];
   const char *rs1_name = riscv_gpr_names_abi[rs1];
   const char *rs2_name = riscv_gpr_names_abi[rs2];
-  unsigned_word tmp, dividend_max;
+  unsigned_word tmp;
   sim_cia pc = riscv_cpu->pc + 4;
 
-  dividend_max = -((unsigned_word) 1 << (WITH_TARGET_WORD_BITSIZE - 1));
-
   switch (op->match)
     {
     case MATCH_DIV:
       TRACE_INSN (cpu, "div %s, %s, %s;  // %s = %s / %s",
 		  rd_name, rs1_name, rs2_name, rd_name, rs1_name, rs2_name);
-      if (riscv_cpu->regs[rs1] == dividend_max && riscv_cpu->regs[rs2] == -1)
-	tmp = dividend_max;
+      if (riscv_cpu->regs[rs2] == -1)
+	tmp = -riscv_cpu->regs[rs1];
       else if (riscv_cpu->regs[rs2])
 	tmp = (signed_word) riscv_cpu->regs[rs1] /
 	  (signed_word) riscv_cpu->regs[rs2];
@@ -793,7 +791,7 @@  execute_m (SIM_CPU *cpu, unsigned_word iw, const struct riscv_opcode *op)
     case MATCH_REM:
       TRACE_INSN (cpu, "rem %s, %s, %s;  // %s = %s %% %s",
 		  rd_name, rs1_name, rs2_name, rd_name, rs1_name, rs2_name);
-      if (riscv_cpu->regs[rs1] == dividend_max && riscv_cpu->regs[rs2] == -1)
+      if (riscv_cpu->regs[rs2] == -1)
 	tmp = 0;
       else if (riscv_cpu->regs[rs2])
 	tmp = (signed_word) riscv_cpu->regs[rs1]