target/arm: Handle FPCR.AH in SVE FTMAD

The negation step in the SVE FTMAD insn mustn't negate a NaN when
FPCR.AH is set.  Pass FPCR.AH to the helper via the SIMD data field,
so we can select the correct behaviour.

Because the operand is known to be negative, negating the operand
is the same as taking the absolute value.  Defer this to the muladd
operation via flags, so that it happens after NaN detection, which
is correct for FPCR.AH.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

diff --git a/target/arm/tcg/sve_helper.c b/target/arm/tcg/sve_helper.c
index bf88bde8a310095ecdcbfce5fb1ceb11767d220e..c12b2600bd7210875275c8617027c38bbe698225 100644 (file)
--- a/target/arm/tcg/sve_helper.c
+++ b/target/arm/tcg/sve_helper.c
@@ -5134,16 +5134,24 @@ void HELPER(sve_ftmad_h)(void *vd, void *vn, void *vm,
         0x3c00, 0xb800, 0x293a, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000,
     };
     intptr_t i, opr_sz = simd_oprsz(desc) / sizeof(float16);
-    intptr_t x = simd_data(desc);
+    intptr_t x = extract32(desc, SIMD_DATA_SHIFT, 3);
+    bool fpcr_ah = extract32(desc, SIMD_DATA_SHIFT + 3, 1);
     float16 *d = vd, *n = vn, *m = vm;
+
     for (i = 0; i < opr_sz; i++) {
         float16 mm = m[i];
         intptr_t xx = x;
+        int flags = 0;
+
         if (float16_is_neg(mm)) {
-            mm = float16_abs(mm);
+            if (fpcr_ah) {
+                flags = float_muladd_negate_product;
+            } else {
+                mm = float16_abs(mm);
+            }
             xx += 8;
         }
-        d[i] = float16_muladd(n[i], mm, coeff[xx], 0, s);
+        d[i] = float16_muladd(n[i], mm, coeff[xx], flags, s);
     }
 }
 
@@ -5157,16 +5165,24 @@ void HELPER(sve_ftmad_s)(void *vd, void *vn, void *vm,
         0x37cd37cc, 0x00000000, 0x00000000, 0x00000000,
     };
     intptr_t i, opr_sz = simd_oprsz(desc) / sizeof(float32);
-    intptr_t x = simd_data(desc);
+    intptr_t x = extract32(desc, SIMD_DATA_SHIFT, 3);
+    bool fpcr_ah = extract32(desc, SIMD_DATA_SHIFT + 3, 1);
     float32 *d = vd, *n = vn, *m = vm;
+
     for (i = 0; i < opr_sz; i++) {
         float32 mm = m[i];
         intptr_t xx = x;
+        int flags = 0;
+
         if (float32_is_neg(mm)) {
-            mm = float32_abs(mm);
+            if (fpcr_ah) {
+                flags = float_muladd_negate_product;
+            } else {
+                mm = float32_abs(mm);
+            }
             xx += 8;
         }
-        d[i] = float32_muladd(n[i], mm, coeff[xx], 0, s);
+        d[i] = float32_muladd(n[i], mm, coeff[xx], flags, s);
     }
 }
 
@@ -5184,16 +5200,24 @@ void HELPER(sve_ftmad_d)(void *vd, void *vn, void *vm,
         0x3e21ee96d2641b13ull, 0xbda8f76380fbb401ull,
     };
     intptr_t i, opr_sz = simd_oprsz(desc) / sizeof(float64);
-    intptr_t x = simd_data(desc);
+    intptr_t x = extract32(desc, SIMD_DATA_SHIFT, 3);
+    bool fpcr_ah = extract32(desc, SIMD_DATA_SHIFT + 3, 1);
     float64 *d = vd, *n = vn, *m = vm;
+
     for (i = 0; i < opr_sz; i++) {
         float64 mm = m[i];
         intptr_t xx = x;
+        int flags = 0;
+
         if (float64_is_neg(mm)) {
-            mm = float64_abs(mm);
+            if (fpcr_ah) {
+                flags = float_muladd_negate_product;
+            } else {
+                mm = float64_abs(mm);
+            }
             xx += 8;
         }
-        d[i] = float64_muladd(n[i], mm, coeff[xx], 0, s);
+        d[i] = float64_muladd(n[i], mm, coeff[xx], flags, s);
     }
 }
 

diff --git a/target/arm/tcg/translate-sve.c b/target/arm/tcg/translate-sve.c
index 2dd4605bb2f61f507ffb06ebd275f11bbe7c09fc..410087c3fbdd333195a3a8d1d5e090e50738b6a8 100644 (file)
--- a/target/arm/tcg/translate-sve.c
+++ b/target/arm/tcg/translate-sve.c
@@ -3685,7 +3685,8 @@ static gen_helper_gvec_3_ptr * const ftmad_fns[4] = {
     gen_helper_sve_ftmad_s, gen_helper_sve_ftmad_d,
 };
 TRANS_FEAT_NONSTREAMING(FTMAD, aa64_sve, gen_gvec_fpst_zzz,
-                        ftmad_fns[a->esz], a->rd, a->rn, a->rm, a->imm,
+                        ftmad_fns[a->esz], a->rd, a->rn, a->rm,
+                        a->imm | (s->fpcr_ah << 3),
                         a->esz == MO_16 ? FPST_A64_F16 : FPST_A64)
 
 /*