diff --git a/target/hexagon/idef-parser/parser-helpers.c b/target/hexagon/idef-parser/parser-helpers.c
index 86511efb62..fd4d196a79 100644
--- a/target/hexagon/idef-parser/parser-helpers.c
+++ b/target/hexagon/idef-parser/parser-helpers.c
@@ -386,13 +386,10 @@ HexValue gen_rvalue_extend(Context *c, YYLTYPE *locp, HexValue *rvalue)
 
     if (rvalue->type == IMMEDIATE) {
         HexValue res = gen_imm_qemu_tmp(c, locp, 64, rvalue->signedness);
-        bool is_unsigned = (rvalue->signedness == UNSIGNED);
-        const char *sign_suffix = is_unsigned ? "u" : "";
         gen_c_int_type(c, locp, 64, rvalue->signedness);
-        OUT(c, locp, " ", &res, " = ");
-        OUT(c, locp, "(", sign_suffix, "int64_t) ");
-        OUT(c, locp, "(", sign_suffix, "int32_t) ");
-        OUT(c, locp, rvalue, ";\n");
+        OUT(c, locp, " ", &res, " = (");
+        gen_c_int_type(c, locp, 64, rvalue->signedness);
+        OUT(c, locp, ")", rvalue, ";\n");
         return res;
     } else {
         HexValue res = gen_tmp(c, locp, 64, rvalue->signedness);
@@ -963,7 +960,12 @@ HexValue gen_cast_op(Context *c,
     if (src->bit_width == target_width) {
         return *src;
     } else if (src->type == IMMEDIATE) {
-        HexValue res = *src;
+        HexValue res;
+        if (src->bit_width < target_width) {
+            res = gen_rvalue_extend(c, locp, src);
+        } else {
+            res = *src;
+        }
         res.bit_width = target_width;
         res.signedness = signedness;
         return res;
diff --git a/tests/tcg/hexagon/fpstuff.c b/tests/tcg/hexagon/fpstuff.c
index 90ce9a6ef3..28f9397155 100644
--- a/tests/tcg/hexagon/fpstuff.c
+++ b/tests/tcg/hexagon/fpstuff.c
@@ -20,6 +20,7 @@
  */
 
 #include <stdio.h>
+#include <float.h>
 
 const int FPINVF_BIT = 1;                 /* Invalid */
 const int FPINVF = 1 << FPINVF_BIT;
@@ -706,6 +707,57 @@ static void check_float2int_convs()
     check_fpstatus(usr, FPINVF);
 }
 
+static void check_float_consts(void)
+{
+    int res32;
+    unsigned long long res64;
+
+    asm("%0 = sfmake(#%1):neg\n\t" : "=r"(res32) : "i"(0xf));
+    check32(res32, 0xbc9e0000);
+
+    asm("%0 = sfmake(#%1):pos\n\t" : "=r"(res32) : "i"(0xf));
+    check32(res32, 0x3c9e0000);
+
+    asm("%0 = dfmake(#%1):neg\n\t" : "=r"(res64) : "i"(0xf));
+    check64(res64, 0xbf93c00000000000ULL);
+
+    asm("%0 = dfmake(#%1):pos\n\t" : "=r"(res64) : "i"(0xf));
+    check64(res64, 0x3f93c00000000000ULL);
+}
+
+static inline unsigned long long dfmpyll(double x, double y)
+{
+    unsigned long long res64;
+    asm("%0 = dfmpyll(%1, %2)" : "=r"(res64) : "r"(x), "r"(y));
+    return res64;
+}
+
+static inline unsigned long long dfmpylh(double acc, double x, double y)
+{
+    unsigned long long res64 = *(unsigned long long *)&acc;
+    asm("%0 += dfmpylh(%1, %2)" : "+r"(res64) : "r"(x), "r"(y));
+    return res64;
+}
+
+static void check_dfmpyxx(void)
+{
+    unsigned long long res64;
+
+    res64 = dfmpyll(DBL_MIN, DBL_MIN);
+    check64(res64, 0ULL);
+    res64 = dfmpyll(-1.0, DBL_MIN);
+    check64(res64, 0ULL);
+    res64 = dfmpyll(DBL_MAX, DBL_MAX);
+    check64(res64, 0x1fffffffdULL);
+
+    res64 = dfmpylh(DBL_MIN, DBL_MIN, DBL_MIN);
+    check64(res64, 0x10000000000000ULL);
+    res64 = dfmpylh(-1.0, DBL_MAX, DBL_MIN);
+    check64(res64, 0xc00fffffffe00000ULL);
+    res64 = dfmpylh(DBL_MAX, 0.0, -1.0);
+    check64(res64, 0x7fefffffffffffffULL);
+}
+
 int main()
 {
     check_compare_exception();
@@ -718,6 +770,8 @@ int main()
     check_sffixupd();
     check_sffms();
     check_float2int_convs();
+    check_float_consts();
+    check_dfmpyxx();
 
     puts(err ? "FAIL" : "PASS");
     return err ? 1 : 0;
diff --git a/target/hexagon/gen_idef_parser_funcs.py b/target/hexagon/gen_idef_parser_funcs.py
index afe68bdb6f..b766798ad5 100644
--- a/target/hexagon/gen_idef_parser_funcs.py
+++ b/target/hexagon/gen_idef_parser_funcs.py
@@ -103,7 +103,15 @@ def main():
                 continue
             if tag.startswith("V6_"):
                 continue
-            if tag.startswith("F"):
+            if ( tag.startswith("F") and
+                 tag not in {
+                     "F2_sfimm_p",
+                     "F2_sfimm_n",
+                     "F2_dfimm_p",
+                     "F2_dfimm_n",
+                     "F2_dfmpyll",
+                     "F2_dfmpylh"
+                 }):
                 continue
             if tag.endswith("_locked"):
                 continue
