From b2ea48df925a6d41f63e88b26dbf3f17cde0f252 Mon Sep 17 00:00:00 2001 From: Mike Frysinger Date: Sat, 6 Jan 2024 23:16:41 -0500 Subject: 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. --- sim/common/cgen-types.h | 6 +++--- 1 file 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. */ -- cgit v1.1