Suggested fix for [b0f84119c8]: TEBCresume(): undefined behavior for INST_LSHIFT

jan.nijtmans · jan.nijtmans · commit 6a3a8ae8ff86 · 2021-12-16T21:02:15.000Z
diff --git a/generic/tclExecute.c b/generic/tclExecute.c
@@ -6379,10 +6379,10 @@ TEBCresume(
 		     * Handle shifts within the native long range.
 		     */
 
-		    if ((size_t) shift < CHAR_BIT*sizeof(long) && (l1 != 0)
+		    if (((size_t) shift < CHAR_BIT*sizeof(long))
 			    && !((l1>0 ? l1 : ~l1) &
-				-(1L<<(CHAR_BIT*sizeof(long) - 1 - shift)))) {
-			lResult = l1 << shift;
+				-(1UL<<(CHAR_BIT*sizeof(long) - 1 - shift)))) {
+			lResult = (unsigned long)l1 << shift;
 			goto longResultOfArithmetic;
 		    }
 		}

Original file line number	Diff line number	Diff line change
`@@ -6379,10 +6379,10 @@ TEBCresume(`
`6379`	`6379`	`* Handle shifts within the native long range.`
`6380`	`6380`	`*/`
`6381`	`6381`
`6382`		`- if ((size_t) shift < CHAR_BIT*sizeof(long) && (l1 != 0)`
	`6382`	`+ if (((size_t) shift < CHAR_BIT*sizeof(long))`
`6383`	`6383`	`&& !((l1>0 ? l1 : ~l1) &`
`6384`		`- -(1L<<(CHAR_BIT*sizeof(long) - 1 - shift)))) {`
`6385`		`- lResult = l1 << shift;`
	`6384`	`+ -(1UL<<(CHAR_BIT*sizeof(long) - 1 - shift)))) {`
	`6385`	`+ lResult = (unsigned long)l1 << shift;`
`6386`	`6386`	`goto longResultOfArithmetic;`
`6387`	`6387`	`}`
`6388`	`6388`	`}`