x86: fix issue with casting in Cvtf2i

UBSAN flags this operation because it detects that arg is being cast directly
to an unsigned type, argBits. this patch fixes this by first casting the
value to a signed int type, then reintrepreting the raw bits of the signed
int into argBits.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/arch/x86/isa/microops/mediaop.isa b/src/arch/x86/isa/microops/mediaop.isa
index cdb3b4899..63e22a23f 100644
--- a/src/arch/x86/isa/microops/mediaop.isa
+++ b/src/arch/x86/isa/microops/mediaop.isa
@@ -1220,9 +1220,11 @@ let {{
                 }
 
                 if (destSize == 4) {
-                    argBits = (uint32_t)arg;
+                    int32_t i_arg = (int32_t)arg;
+                    argBits = *((uint32_t*)&i_arg);
                 } else {
-                    argBits = (uint64_t)arg;
+                    int64_t i_arg = (int64_t)arg;
+                    argBits = *((uint64_t*)&i_arg);
                 }
                 int destHiIndex = destStart + (i + 1) * destSizeBits - 1;
                 int destLoIndex = destStart + (i + 0) * destSizeBits;