Re: [PATCH v2 5/6] target/riscv: Update address modify functions to take into account pointer masking

[Richard Henderson]

On 12/24/23 15:48, Alexey Baturo wrote:
From: Alexey Baturo <baturo.ale...@gmail.com>
Signed-off-by: Alexey Baturo <baturo.ale...@gmail.com>
---
  target/riscv/translate.c     | 23 +++++++++++++++++++++--
  target/riscv/vector_helper.c | 10 ++++++++++
  2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index 1eb501e0d3..c0c5030e05 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -575,11 +575,20 @@ static void gen_jal(DisasContext *ctx, int rd, 
target_ulong imm)
  /* Compute a canonical address from a register plus offset. */
  static TCGv get_address(DisasContext *ctx, int rs1, int imm)
  {
+    int pmlen = riscv_pm_get_pmlen(ctx->pm_pmm);
      TCGv addr = tcg_temp_new();
      TCGv src1 = get_gpr(ctx, rs1, EXT_NONE);
  
      tcg_gen_addi_tl(addr, src1, imm);
-    if (get_address_xl(ctx) == MXL_RV32) {
+    if (ctx->pm_pmm) {
+        tcg_gen_shli_tl(addr, addr, pmlen);
+        /* sign extend address by first non-masked bit otherwise zero extend */
+        if (ctx->pm_signext) {
+            tcg_gen_sari_tl(addr, addr, pmlen);
+        } else {
+            tcg_gen_shri_tl(addr, addr, pmlen);
+        }
+    } else if (get_address_xl(ctx) == MXL_RV32) {
          tcg_gen_ext32u_tl(addr, addr);
      }
  
@@ -589,11 +598,21 @@ static TCGv get_address(DisasContext *ctx, int rs1, int imm)
  /* Compute a canonical address from a register plus reg offset. */
  static TCGv get_address_indexed(DisasContext *ctx, int rs1, TCGv offs)
  {
+    int pmlen = riscv_pm_get_pmlen(ctx->pm_pmm);
      TCGv addr = tcg_temp_new();
      TCGv src1 = get_gpr(ctx, rs1, EXT_NONE);
  
      tcg_gen_add_tl(addr, src1, offs);
-    if (get_xl(ctx) == MXL_RV32) {
+    /* sign extend address by first non-masked bit */
+    if (ctx->pm_pmm) {
+        tcg_gen_shli_tl(addr, addr, pmlen);
+        /* sign extend address by first non-masked bit otherwise zero extend */
+        if (ctx->pm_signext) {
+            tcg_gen_sari_tl(addr, addr, pmlen);
+        } else {
+            tcg_gen_shri_tl(addr, addr, pmlen);
+        }
+    } else if (get_xl(ctx) == MXL_RV32) {
          tcg_gen_ext32u_tl(addr, addr);

Use tcg_gen_{s}extract_tl instead of two shifts.

Also, it looks like it would be worth doing all of this once in 
riscv_tr_init_disas_context:

    if (get_xl(ctx) == MXL_RV32) {
        ctx->addr_width = 32;
        ctx->addr_signed = false;
    } else {
        pm_pmm = FIELD_EX32(tb_flags, TB_FLAGS, PM_PMM);
        ctx->addr_width = 64 - riscv_pm_get_pmlen(pm_pmm);
        ctx->addr_signed = FIELD_EX32(tb_flags, TB_FLAGS, PM_SIGNEXTEND);
    }

then here in get_address_indexed

    if (ctx->addr_signed) {
        tcg_gen_sextract_tl(addr, addr, ctx->addr_width);
    } else {
        tcg_gen_extract_tl(addr, addr, ctx->addr_width);
    }

diff --git a/target/riscv/vector_helper.c b/target/riscv/vector_helper.c
index 8e7a8e80a0..faa8f5820d 100644
--- a/target/riscv/vector_helper.c
+++ b/target/riscv/vector_helper.c
@@ -94,6 +94,16 @@ static inline uint32_t vext_max_elems(uint32_t desc, 
uint32_t log2_esz)
  
  static inline target_ulong adjust_addr(CPURISCVState *env, target_ulong addr)
  {
+    RISCVPmPmm pmm = riscv_pm_get_pmm(env);
+    int pmlen = riscv_pm_get_pmlen(pmm);
+    bool signext = !riscv_cpu_bare_mode(env);
+    addr = addr << pmlen;
+    /* sign/zero extend masked address by N-1 bit */
+    if (signext) {
+        addr = (target_long)addr >> pmlen;
+    } else {
+        addr = addr >> pmlen;
+    }
      return addr;
  }

I think you could usefully exit early when likely(pmm == PMM_FIELD_DISABLED), avoiding the 
other computation.


r~