On 8/4/21 4:53 PM, LIU Zhiwei wrote:
+static TCGv gpr_src_u(DisasContext *ctx, int reg_num)
+{
+ if (reg_num == 0) {
+ return ctx->zero;
+ }
+ if (ctx->uxl32) {
+ tcg_gen_ext32u_tl(cpu_gpr[reg_num], cpu_gpr[reg_num]);
+ }
+ return cpu_gpr[reg_num];
+}
+
+static TCGv gpr_src_s(DisasContext *ctx, int reg_num)
+{
+ if (reg_num == 0) {
+ return ctx->zero;
+ }
+ if (ctx->uxl32) {
+ tcg_gen_ext32s_tl(cpu_gpr[reg_num], cpu_gpr[reg_num]);
+ }
+ return cpu_gpr[reg_num];
+}
This is bad: you cannot modify the source registers like this.
These incorrect modifications will be visible to the kernel on transition back
to S-mode.
+static bool gen_branch_u(DisasContext *ctx, arg_b *a, TCGCond cond)
+{
+ TCGv src1 = gpr_src_u(ctx, a->rs1);
+ TCGv src2 = gpr_src_u(ctx, a->rs2);
+
+ return gen_branch_internal(ctx, a, cond, src1, src2);
+}
This is unnecessary. Unsigned comparisons work just fine with sign-extended values. It
will be simpler to keep all values sign-extended.
r~
