[gcc(refs/vendors/redhat/heads/gcc-8-branch)] [PATCH] Backport fix for PR target/989r2

[gcc(refs/vendors/redhat/heads/gcc-8-branch)] [PATCH] Backport fix for PR target/989r2

[Jakub Jelinek]

https://gcc.gnu.org/g:009fd47fe039148de4e0e69c57b336fab8e77283

commit 009fd47fe039148de4e0e69c57b336fab8e77283
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Mon Apr 26 18:26:16 2021 -0400

    [PATCH] Backport fix for PR target/989r2
    
    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 fixed the test
    so the operands are reversed.  I then folded the load immediate into the
    compare instruction.
    
    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 added a test case that runs on PowerPC 32-bit Linux systems and it calls
    the __trampoline_setup function with a larger buffer size than the
    compiler uses.  The test is not run on 64-bit systems, since the function
    __trampoline_setup is not called.  I also limited the test to just Linux
    systems, in case trampolines are handled differently in other systems.
    
    libgcc/
    2021-04-26  Michael Meissner  <meissner@linux.ibm.com>
    
            PR target/98952
            * config/rs6000/tramp.S (__trampoline_setup, elfv1 #ifdef): Fix
            trampoline size comparison in 32-bit by reversing test and
            combining load immediate with compare.  Fix backported from trunk
            change on 4/23, 886b6c1e8af502b69e3f318b9830b73b88215878.
            (__trampoline_setup, elfv2 #ifdef): Fix trampoline size comparison
            in 32-bit by reversing test and combining load immediate with
            compare.
    
    gcc/testsuite/
    2021-04-26  Michael Meissner  <meissner@linux.ibm.com>
    
            PR target/98952
            * gcc.target/powerpc/pr98952.c: New test.  Test backported from
            trunk change on 4/23, 886b6c1e8af502b69e3f318b9830b73b88215878.

Diff:
---
 gcc/testsuite/gcc.target/powerpc/pr98952.c | 28 ++++++++++++++++++++++++++++
 libgcc/config/rs6000/tramp.S               |  6 ++----
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/gcc/testsuite/gcc.target/powerpc/pr98952.c b/gcc/testsuite/gcc.target/powerpc/pr98952.c
new file mode 100644
index 00000000000..c487fbc403e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr98952.c
@@ -0,0 +1,28 @@
+/* { dg-do run { target { powerpc*-*-linux* && ilp32 } } } */
+/* { dg-options "-O2" } */
+
+/* PR 96983 reported that the test in libgcc's tramp.S was backwards and it
+   would abort if the trampoline size passed to the function was greater than
+   the size the runtime was expecting (40).  It should abort if the size is less
+   than 40, not greater than 40.  This test creates a call to __trampoline_setup
+   with a much larger buffer to make sure the function does not abort.
+
+   We do not run this test on 64-bit since __trampoline_setup is not present in
+   64-bit systems.
+
+   We only run the test under Linux in case the other systems have some
+   different variant for __trampoline_setup.  */
+
+#ifndef SIZE
+#define SIZE 100
+#endif
+
+extern void __trampoline_setup (int *, unsigned, void *, void *);
+
+int main (void)
+{
+  int tramp[SIZE / sizeof (int)];
+
+  __trampoline_setup (tramp, SIZE, 0, 0);
+  return 0;
+}
diff --git a/libgcc/config/rs6000/tramp.S b/libgcc/config/rs6000/tramp.S
index 19ea57838fc..e3b11b13954 100644
--- a/libgcc/config/rs6000/tramp.S
+++ b/libgcc/config/rs6000/tramp.S
@@ -62,8 +62,7 @@ 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
@@ -147,8 +146,7 @@ FUNC_START(__trampoline_setup)
 	addis 7,2,.LC0@toc@ha
 	ld 7,.LC0@toc@l(7)	/* trampoline address -8 */
 
-	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,r4,3		/* # doublewords to move */
 	addi	r9,r3,-8	/* adjust pointer for stdu */
 	mtctr	r4