[PATCH] Fix logic error in 32-bit trampolines, PR target/98952

Michael Meissner meissner@linux.ibm.com
Fri Apr 9 21:09:07 GMT 2021

Fix logic error in 32-bit trampolines, PR target/98952.

The test in the PowerPC 32-bit trampoline support is backwards.  It aborts
if the trampoline size is greater than the expected size.  It should abort
when the trampoline size is less than the expected size.

I verified this by creating a 32-bit trampoline program and manually
changing the size of the trampoline to be 48 instead of 40.  The program
aborted with the larger size.  I updated this code and ran the test again
and it passed.

I did a bootstrap build on a big endian power8 system that supports both
32-bit and 64-bit executables, and there were no regressions.  Can I check
this patch into the trunk?

2021-04-09  Michael Meissner  <meissner@linux.ibm.com>

	PR target/98952
	* config/rs6000/tramp.S (__trampoline_setup): Fix trampoline size
	comparison in 32-bit.
 libgcc/config/rs6000/tramp.S | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/libgcc/config/rs6000/tramp.S b/libgcc/config/rs6000/tramp.S
index 4236a82b402..6b61d892da6 100644
--- a/libgcc/config/rs6000/tramp.S
+++ b/libgcc/config/rs6000/tramp.S
@@ -64,8 +64,7 @@ FUNC_START(__trampoline_setup)
         mflr	r11
         addi	r7,r11,trampoline_initial-4-.LCF0 /* trampoline address -4 */
-	li	r8,trampoline_size	/* verify that the trampoline is big enough */
-	cmpw	cr1,r8,r4
+	cmpwi	cr1,r4,trampoline_size	/* verify that the trampoline is big enough */
 	srwi	r4,r4,2		/* # words to move */
 	addi	r9,r3,-4	/* adjust pointer for lwzu */
 	mtctr	r4

Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

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