Hexagon (target/hexagon) Add overrides for S2_asr_r_r_sat/S2_asl_r_r_sat

These instructions will not be generated by idef-parser, so we override
them manually.

Test cases added to tests/tcg/hexagon/usr.c

Co-authored-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com>
Signed-off-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20221108162906.3166-4-tsimpson@quicinc.com>

2 files changed, 113 insertions, 1 deletions

diff --git a/target/hexagon/gen_tcg.h b/target/hexagon/gen_tcg.h
index 50634ac..b5fe22a 100644
--- a/target/hexagon/gen_tcg.h
+++ b/target/hexagon/gen_tcg.h
@@ -1,5 +1,5 @@
 /*
- *  Copyright(c) 2019-2021 Qualcomm Innovation Center, Inc. All Rights Reserved.
+ *  Copyright(c) 2019-2022 Qualcomm Innovation Center, Inc. All Rights Reserved.
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -612,6 +612,14 @@
         tcg_temp_free(tmp); \
     } while (0)
 
+/* r0 = asr(r1, r2):sat */
+#define fGEN_TCG_S2_asr_r_r_sat(SHORTCODE) \
+    gen_asr_r_r_sat(RdV, RsV, RtV)
+
+/* r0 = asl(r1, r2):sat */
+#define fGEN_TCG_S2_asl_r_r_sat(SHORTCODE) \
+    gen_asl_r_r_sat(RdV, RsV, RtV)
+
 /* Floating point */
 #define fGEN_TCG_F2_conv_sf2df(SHORTCODE) \
     gen_helper_conv_sf2df(RddV, cpu_env, RsV)
diff --git a/target/hexagon/genptr.c b/target/hexagon/genptr.c
index 85416dd..cd3d745 100644
--- a/target/hexagon/genptr.c
+++ b/target/hexagon/genptr.c
@@ -456,6 +456,110 @@ static TCGv gen_8bitsof(TCGv result, TCGv value)
     return result;
 }
 
+/* Shift left with saturation */
+static void gen_shl_sat(TCGv dst, TCGv src, TCGv shift_amt)
+{
+    TCGv sh32 = tcg_temp_new();
+    TCGv dst_sar = tcg_temp_new();
+    TCGv ovf = tcg_temp_new();
+    TCGv satval = tcg_temp_new();
+    TCGv min = tcg_constant_tl(0x80000000);
+    TCGv max = tcg_constant_tl(0x7fffffff);
+
+    /*
+     *    Possible values for shift_amt are 0 .. 64
+     *    We need special handling for values above 31
+     *
+     *    sh32 = shift & 31;
+     *    dst = sh32 == shift ? src : 0;
+     *    dst <<= sh32;
+     *    dst_sar = dst >> sh32;
+     *    satval = src < 0 ? min : max;
+     *    if (dst_asr != src) {
+     *        usr.OVF |= 1;
+     *        dst = satval;
+     *    }
+     */
+
+    tcg_gen_andi_tl(sh32, shift_amt, 31);
+    tcg_gen_movcond_tl(TCG_COND_EQ, dst, sh32, shift_amt,
+                       src, tcg_constant_tl(0));
+    tcg_gen_shl_tl(dst, dst, sh32);
+    tcg_gen_sar_tl(dst_sar, dst, sh32);
+    tcg_gen_movcond_tl(TCG_COND_LT, satval, src, tcg_constant_tl(0), min, max);
+
+    tcg_gen_setcond_tl(TCG_COND_NE, ovf, dst_sar, src);
+    tcg_gen_shli_tl(ovf, ovf, reg_field_info[USR_OVF].offset);
+    tcg_gen_or_tl(hex_new_value[HEX_REG_USR], hex_new_value[HEX_REG_USR], ovf);
+
+    tcg_gen_movcond_tl(TCG_COND_EQ, dst, dst_sar, src, dst, satval);
+
+    tcg_temp_free(sh32);
+    tcg_temp_free(dst_sar);
+    tcg_temp_free(ovf);
+    tcg_temp_free(satval);
+}
+
+static void gen_sar(TCGv dst, TCGv src, TCGv shift_amt)
+{
+    /*
+     *  Shift arithmetic right
+     *  Robust when shift_amt is >31 bits
+     */
+    TCGv tmp = tcg_temp_new();
+    tcg_gen_umin_tl(tmp, shift_amt, tcg_constant_tl(31));
+    tcg_gen_sar_tl(dst, src, tmp);
+    tcg_temp_free(tmp);
+}
+
+/* Bidirectional shift right with saturation */
+static void gen_asr_r_r_sat(TCGv RdV, TCGv RsV, TCGv RtV)
+{
+    TCGv shift_amt = tcg_temp_local_new();
+    TCGLabel *positive = gen_new_label();
+    TCGLabel *done = gen_new_label();
+
+    tcg_gen_sextract_i32(shift_amt, RtV, 0, 7);
+    tcg_gen_brcondi_tl(TCG_COND_GE, shift_amt, 0, positive);
+
+    /* Negative shift amount => shift left */
+    tcg_gen_neg_tl(shift_amt, shift_amt);
+    gen_shl_sat(RdV, RsV, shift_amt);
+    tcg_gen_br(done);
+
+    gen_set_label(positive);
+    /* Positive shift amount => shift right */
+    gen_sar(RdV, RsV, shift_amt);
+
+    gen_set_label(done);
+
+    tcg_temp_free(shift_amt);
+}
+
+/* Bidirectional shift left with saturation */
+static void gen_asl_r_r_sat(TCGv RdV, TCGv RsV, TCGv RtV)
+{
+    TCGv shift_amt = tcg_temp_local_new();
+    TCGLabel *positive = gen_new_label();
+    TCGLabel *done = gen_new_label();
+
+    tcg_gen_sextract_i32(shift_amt, RtV, 0, 7);
+    tcg_gen_brcondi_tl(TCG_COND_GE, shift_amt, 0, positive);
+
+    /* Negative shift amount => shift right */
+    tcg_gen_neg_tl(shift_amt, shift_amt);
+    gen_sar(RdV, RsV, shift_amt);
+    tcg_gen_br(done);
+
+    gen_set_label(positive);
+    /* Positive shift amount => shift left */
+    gen_shl_sat(RdV, RsV, shift_amt);
+
+    gen_set_label(done);
+
+    tcg_temp_free(shift_amt);
+}
+
 static intptr_t vreg_src_off(DisasContext *ctx, int num)
 {
     intptr_t offset = offsetof(CPUHexagonState, VRegs[num]);