Fix issue 20089: Handle extra case in fixresult_complex87

Author: marler8997

src/dmd/backend/cg87.d

@@ -3646,6 +3646,25 @@ void fixresult_complex87(ref CodeBuilder cdb,elem *e,regm_t retregs,regm_t *pret
         cdb.genf2(0xDD,modregrm(3,3,0));        // FPOP
         pop87();
     }
+    else if (tym == TYllong)
+    {
+        assert(retregs & mST01, "this float expression is not implemented");
+        if (!(*pretregs & mCX))
+        {
+            printf("*pretregs = %d is not implemented\n", *pretregs);
+            assert(0, "moving cfloat to register other than CX is not implemented");
+        }
+        pop87();
+        cdb.genfltreg(ESC(MFfloat,1),BX,0);     // FSTP floatreg
+        genfwait(cdb);
+        getregs(cdb,mCX);
+        cdb.genfltreg(LOD, CX, 4);              // MOV RCX,floatreg
+
+        pop87();
+        cdb.genfltreg(ESC(MFfloat,1),BX,0);     // FSTP floatreg
+        genfwait(cdb);
+        cdb.genfltreg(LOD, CX, 0);              // MOV RCX,floatreg
+    }
     else if (tym == TYcfloat && *pretregs & (mAX|mDX) && retregs & mST01)
     {
         if (*pretregs & mPSW && !(retregs & mPSW))

test/runnable/test18772.d

@@ -1,12 +1,20 @@
-float fun(cfloat z)
+float getreal(cfloat z)
 {
     return z.re;
 }
+float geti(cfloat z)
+{
+     return z.im;
+}
 
 void main()
 {
     cfloat[1] A;
     float[1] B;
     int i = 0;
-    double C = fun(A[i] * B[i]);
+    A[0] = 2.0f + 4i;
+    B[0] = 3.0f;
+    assert(((2.0f + 4i) * 3.0f).re == getreal(A[i] * B[i]));
+    //assert(((2.0f + 4i) * 3.0f).im == geti(A[i] * B[i]));
+    double C = getreal(A[i] * B[i]);
 }