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authorMike Frysinger <vapier@gentoo.org>2024-01-06 23:16:41 -0500
committerMike Frysinger <vapier@gentoo.org>2024-01-08 20:01:05 -0500
commitb2ea48df925a6d41f63e88b26dbf3f17cde0f252 (patch)
tree90faff9a96d7518eb11b590eaa2327c3b28c67c8 /sim/common
parent707877ab59c6d0cbcb58cb5d467ab5f0d071a935 (diff)
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sim: cgen: rework DI macros to avoid signed left shifts
The cgen code uses DI as int64_t and UDI as uint64_t. The DI macros are used to construct 64-bit values from 32-bit values (for the low and high parts). The MAKEDI macro casts the high 32-bit value to a signed 32-bit value before shifting. If this created a negative value, this would be undefined behavior according to the C standard. All we care about is shifting the 32-bits as they are to the high 32-bits, not caring about sign extension (since there's nothing left to shift into), and the low 32-bits being empty. This is what we get from shifting an unsigned value, so cast it to unsigned 32-bit to avoid undefined behavior. While we're here, change the SETLODI macro to truncate the lower value to 32-bits before we set it. If it was passing in a 64-bit value, those high bits would get included too, and that's not what we want. Similarly, tweak the SETHIDI macro to cast the value to an unsigned 64-bit instead of a signed 64-bit. If the value was only 32-bits, the behavior would be the same. If it happened to be signed 64-bit, it would trigger the undefined behavior too.
Diffstat (limited to 'sim/common')
-rw-r--r--sim/common/cgen-types.h6
1 files changed, 3 insertions, 3 deletions
diff --git a/sim/common/cgen-types.h b/sim/common/cgen-types.h
index 01a3ee9..24c2b89 100644
--- a/sim/common/cgen-types.h
+++ b/sim/common/cgen-types.h
@@ -72,9 +72,9 @@ typedef int64_t DI;
typedef uint64_t UDI;
#define GETLODI(di) ((SI) (di))
#define GETHIDI(di) ((SI) ((UDI) (di) >> 32))
-#define SETLODI(di, val) ((di) = (((di) & 0xffffffff00000000LL) | (val)))
-#define SETHIDI(di, val) ((di) = (((di) & 0xffffffffLL) | (((DI) (val)) << 32)))
-#define MAKEDI(hi, lo) ((((DI) (SI) (hi)) << 32) | ((UDI) (USI) (lo)))
+#define SETLODI(di, val) ((di) = (((di) & 0xffffffff00000000LL) | (USI) (val)))
+#define SETHIDI(di, val) ((di) = (((di) & 0xffffffffLL) | (((UDI) (val)) << 32)))
+#define MAKEDI(hi, lo) ((DI) (((UDI) (hi) << 32) | (UDI) (USI) (lo)))
/* These are used to record extracted raw data from an instruction, among other
things. It must be a host data type, and not a target one. */