target/ppc: Implement DCTFIXQQ

Implement the following PowerISA v3.1 instruction:
dctfixqq: DFP Convert To Fixed Quadword Quad

Signed-off-by: Luis Pires <luis.pires@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20211029192417.400707-8-luis.pires@eldorado.org.br>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

target/ppc/dfp_helper.c

@@ -51,6 +51,11 @@ static void set_dfp128(ppc_fprp_t *dfp, ppc_vsr_t *src)
     dfp[1].VsrD(0) = src->VsrD(1);
 }
 
+static void set_dfp128_to_avr(ppc_avr_t *dst, ppc_vsr_t *src)
+{
+    *dst = *src;
+}
+
 struct PPC_DFP {
     CPUPPCState *env;
     ppc_vsr_t vt, va, vb;
@@ -1020,6 +1025,53 @@ void helper_##op(CPUPPCState *env, ppc_fprp_t *t, ppc_fprp_t *b)              \
 DFP_HELPER_CTFIX(dctfix, 64)
 DFP_HELPER_CTFIX(dctfixq, 128)
 
+void helper_DCTFIXQQ(CPUPPCState *env, ppc_avr_t *t, ppc_fprp_t *b)
+{
+    struct PPC_DFP dfp;
+    dfp_prepare_decimal128(&dfp, 0, b, env);
+
+    if (unlikely(decNumberIsSpecial(&dfp.b))) {
+        uint64_t invalid_flags = FP_VX | FP_VXCVI;
+        if (decNumberIsInfinite(&dfp.b)) {
+            if (decNumberIsNegative(&dfp.b)) {
+                dfp.vt.VsrD(0) = INT64_MIN;
+                dfp.vt.VsrD(1) = 0;
+            } else {
+                dfp.vt.VsrD(0) = INT64_MAX;
+                dfp.vt.VsrD(1) = UINT64_MAX;
+            }
+        } else { /* NaN */
+            dfp.vt.VsrD(0) = INT64_MIN;
+            dfp.vt.VsrD(1) = 0;
+            if (decNumberIsSNaN(&dfp.b)) {
+                invalid_flags |= FP_VXSNAN;
+            }
+        }
+        dfp_set_FPSCR_flag(&dfp, invalid_flags, FP_VE);
+    } else if (unlikely(decNumberIsZero(&dfp.b))) {
+        dfp.vt.VsrD(0) = 0;
+        dfp.vt.VsrD(1) = 0;
+    } else {
+        decNumberToIntegralExact(&dfp.b, &dfp.b, &dfp.context);
+        decNumberIntegralToInt128(&dfp.b, &dfp.context,
+                &dfp.vt.VsrD(1), &dfp.vt.VsrD(0));
+        if (decContextTestStatus(&dfp.context, DEC_Invalid_operation)) {
+            if (decNumberIsNegative(&dfp.b)) {
+                dfp.vt.VsrD(0) = INT64_MIN;
+                dfp.vt.VsrD(1) = 0;
+            } else {
+                dfp.vt.VsrD(0) = INT64_MAX;
+                dfp.vt.VsrD(1) = UINT64_MAX;
+            }
+            dfp_set_FPSCR_flag(&dfp, FP_VX | FP_VXCVI, FP_VE);
+        } else {
+            dfp_check_for_XX(&dfp);
+        }
+    }
+
+    set_dfp128_to_avr(t, &dfp.vt);
+}
+
 static inline void dfp_set_bcd_digit_64(ppc_vsr_t *t, uint8_t digit,
                                         unsigned n)
 {

target/ppc/helper.h

@@ -739,6 +739,7 @@ DEF_HELPER_3(dcffixq, void, env, fprp, fprp)
 DEF_HELPER_3(DCFFIXQQ, void, env, fprp, avr)
 DEF_HELPER_3(dctfix, void, env, fprp, fprp)
 DEF_HELPER_3(dctfixq, void, env, fprp, fprp)
+DEF_HELPER_3(DCTFIXQQ, void, env, avr, fprp)
 DEF_HELPER_4(ddedpd, void, env, fprp, fprp, i32)
 DEF_HELPER_4(ddedpdq, void, env, fprp, fprp, i32)
 DEF_HELPER_4(denbcd, void, env, fprp, fprp, i32)

target/ppc/insn32.decode

@@ -54,6 +54,10 @@
 %x_frtp         22:4 !function=times_2
 @X_frtp_vrb     ...... ....0 ..... vrb:5 .......... .           &X_frtp_vrb frtp=%x_frtp
 
+&X_vrt_frbp     vrt frbp
+%x_frbp         12:4 !function=times_2
+@X_vrt_frbp     ...... vrt:5 ..... ....0 .......... .           &X_vrt_frbp frbp=%x_frbp
+
 ### Fixed-Point Load Instructions
 
 LBZ             100010 ..... ..... ................     @D
@@ -167,6 +171,7 @@ SETNBCR         011111 ..... ..... ----- 0111100000 -   @X_bi
 ### Decimal Floating-Point Conversion Instructions
 
 DCFFIXQQ        111111 ..... 00000 ..... 1111100010 -   @X_frtp_vrb
+DCTFIXQQ        111111 ..... 00001 ..... 1111100010 -   @X_vrt_frbp
 
 ## Vector Bit Manipulation Instruction
 

target/ppc/translate/dfp-impl.c.inc

@@ -247,3 +247,20 @@ static bool trans_DCFFIXQQ(DisasContext *ctx, arg_DCFFIXQQ *a)
 
     return true;
 }
+
+static bool trans_DCTFIXQQ(DisasContext *ctx, arg_DCTFIXQQ *a)
+{
+    TCGv_ptr rt, rb;
+
+    REQUIRE_INSNS_FLAGS2(ctx, DFP);
+    REQUIRE_FPU(ctx);
+    REQUIRE_VECTOR(ctx);
+
+    rt = gen_avr_ptr(a->vrt);
+    rb = gen_fprp_ptr(a->frbp);
+    gen_helper_DCTFIXQQ(cpu_env, rt, rb);
+    tcg_temp_free_ptr(rt);
+    tcg_temp_free_ptr(rb);
+
+    return true;
+}