[Qemu-devel] [PATCH] target-mips: fix mipsdsp_mul_q31_q31

[Petar Jovanovic]

From: Petar Jovanovic <address@hidden>

Multiplication of two fractional word elements is not correct when sign
extension/promotion is needed. This change fixes it by adding correct
casts from unsigned to signed values.
In addition, the tests (dpaq_sa_l_w.c and dpsq_sa_l_w.c) have been extended
to trigger the current issue.

Signed-off-by: Petar Jovanovic <address@hidden>
---
 target-mips/dsp_helper.c                |    2 +-
 tests/tcg/mips/mips32-dsp/dpaq_sa_l_w.c |   64 +++++++++++++++++++++++++++----
 tests/tcg/mips/mips32-dsp/dpsq_sa_l_w.c |    4 +-
 3 files changed, 59 insertions(+), 11 deletions(-)

diff --git a/target-mips/dsp_helper.c b/target-mips/dsp_helper.c
index 93f5d9e..b088a25 100644
--- a/target-mips/dsp_helper.c
+++ b/target-mips/dsp_helper.c
@@ -583,7 +583,7 @@ static inline int64_t mipsdsp_mul_q31_q31(int32_t ac, 
uint32_t a, uint32_t b,
         temp = (0x01ull << 63) - 1;
         set_DSPControl_overflow_flag(1, 16 + ac, env);
     } else {
-        temp = ((uint64_t)a * (uint64_t)b) << 1;
+        temp = ((int64_t)(int32_t)a * (int32_t)b) << 1;
     }
 
     return temp;
diff --git a/tests/tcg/mips/mips32-dsp/dpaq_sa_l_w.c 
b/tests/tcg/mips/mips32-dsp/dpaq_sa_l_w.c
index ce86484..cbf9007 100644
--- a/tests/tcg/mips/mips32-dsp/dpaq_sa_l_w.c
+++ b/tests/tcg/mips/mips32-dsp/dpaq_sa_l_w.c
@@ -14,7 +14,7 @@ int main()
     resultdsp = 0x01;
     __asm
         ("mthi        %0, $ac1\n\t"
-         "mtlo        %0, $ac1\n\t"
+         "mtlo        %1, $ac1\n\t"
          "dpaq_sa.l.w $ac1, %3, %4\n\t"
          "mfhi        %0,   $ac1\n\t"
          "mflo        %1,   $ac1\n\t"
@@ -27,8 +27,8 @@ int main()
     assert(ach == resulth);
     assert(acl == resultl);
 
-    ach = 0x12;
-    acl = 0x48;
+    ach = 0x00000012;
+    acl = 0x00000048;
     rs  = 0x80000000;
     rt  = 0x80000000;
 
@@ -37,7 +37,7 @@ int main()
     resultdsp = 0x01;
     __asm
         ("mthi        %0, $ac1\n\t"
-         "mtlo        %0, $ac1\n\t"
+         "mtlo        %1, $ac1\n\t"
          "dpaq_sa.l.w $ac1, %3, %4\n\t"
          "mfhi        %0,   $ac1\n\t"
          "mflo        %1,   $ac1\n\t"
@@ -51,16 +51,64 @@ int main()
     assert(acl == resultl);
 
     ach = 0x741532A0;
-    acl = 0xfceabb08;
+    acl = 0xFCEABB08;
     rs  = 0x80000000;
     rt  = 0x80000000;
 
-    resulth   = 0x7fffffff;
-    resultl   = 0xffffffff;
+    resulth   = 0x7FFFFFFF;
+    resultl   = 0xFFFFFFFF;
     resultdsp = 0x01;
     __asm
         ("mthi        %0, $ac1\n\t"
-         "mtlo        %0, $ac1\n\t"
+         "mtlo        %1, $ac1\n\t"
+         "dpaq_sa.l.w $ac1, %3, %4\n\t"
+         "mfhi        %0,   $ac1\n\t"
+         "mflo        %1,   $ac1\n\t"
+         "rddsp       %2\n\t"
+         : "+r"(ach), "+r"(acl), "=r"(dsp)
+         : "r"(rs), "r"(rt)
+        );
+    dsp = (dsp >> 17) & 0x01;
+    assert(dsp == resultdsp);
+    assert(ach == resulth);
+    assert(acl == resultl);
+
+    ach = 0;
+    acl = 0;
+    rs  = 0xC0000000;
+    rt  = 0x7FFFFFFF;
+
+    resulth   = 0xC0000000;
+    resultl   = 0x80000000;
+    resultdsp = 0;
+    __asm
+        ("wrdsp       $0\n\t"
+         "mthi        %0, $ac1\n\t"
+         "mtlo        %1, $ac1\n\t"
+         "dpaq_sa.l.w $ac1, %3, %4\n\t"
+         "mfhi        %0,   $ac1\n\t"
+         "mflo        %1,   $ac1\n\t"
+         "rddsp       %2\n\t"
+         : "+r"(ach), "+r"(acl), "=r"(dsp)
+         : "r"(rs), "r"(rt)
+        );
+    dsp = (dsp >> 17) & 0x01;
+    assert(dsp == resultdsp);
+    assert(ach == resulth);
+    assert(acl == resultl);
+
+    ach = 0x20000000;
+    acl = 0;
+    rs  = 0xE0000000;
+    rt  = 0x7FFFFFFF;
+
+    resulth   = 0;
+    resultl   = 0x40000000;
+    resultdsp = 0;
+    __asm
+        ("wrdsp       $0\n\t"
+         "mthi        %0, $ac1\n\t"
+         "mtlo        %1, $ac1\n\t"
          "dpaq_sa.l.w $ac1, %3, %4\n\t"
          "mfhi        %0,   $ac1\n\t"
          "mflo        %1,   $ac1\n\t"
diff --git a/tests/tcg/mips/mips32-dsp/dpsq_sa_l_w.c 
b/tests/tcg/mips/mips32-dsp/dpsq_sa_l_w.c
index b7b73fd..eda3b14 100644
--- a/tests/tcg/mips/mips32-dsp/dpsq_sa_l_w.c
+++ b/tests/tcg/mips/mips32-dsp/dpsq_sa_l_w.c
@@ -9,8 +9,8 @@ int main()
 
     rs      = 0xBC0123AD;
     rt      = 0x01643721;
-    resulth = 0xfdf4cbe0;
-    resultl = 0xd138776b;
+    resulth = 0x00BD3A22;
+    resultl = 0xD138776B;
     resultdsp = 0x00;
     __asm
         ("mthi  %0, $ac1\n\t"
-- 
1.7.9.5