diff mbox series

[committed,PR,rtl-optimization/116544] Fix test for promoted subregs

Message ID 734cff63-894e-417c-a07c-4ce31ef2df2e@gmail.com
State New
Headers show
Series [committed,PR,rtl-optimization/116544] Fix test for promoted subregs | expand

Commit Message

Jeff Law Sept. 2, 2024, 4:19 a.m. UTC 
This is a small bug in the ext-dce code's handling of promoted subregs.

Essentially when we see a promoted subreg we need to make additional bit 
groups live as various parts of the RTL path know that an extension of a 
suitably promoted subreg can be trivially eliminated.

When I added support for dealing with this quirk I failed to account for 
the larger modes properly and it ignored the case when the size of the 
inner object was > 32 bits.  Opps.

This does _not_ fix the outstanding x86 issue.  That's caused by 
something completely different and more concerning ;(

Bootstrapped and regression tested on x86.  Obviously fixes the testcase 
on riscv as well.

Pushing to the trunk.

jeff
commit 0562976d62e095f3a00c799288dee4e5b20114e2
Author: Jeff Law <jlaw@ventanamicro.com>
Date:   Sun Sep 1 22:16:04 2024 -0600

    [committed][PR rtl-optimization/116544] Fix test for promoted subregs
    
    This is a small bug in the ext-dce code's handling of promoted subregs.
    
    Essentially when we see a promoted subreg we need to make additional bit groups
    live as various parts of the RTL path know that an extension of a suitably
    promoted subreg can be trivially eliminated.
    
    When I added support for dealing with this quirk I failed to account for the
    larger modes properly and it ignored the case when the size of the inner object
    was > 32 bits.  Opps.
    
    This does _not_ fix the outstanding x86 issue.  That's caused by something
    completely different and more concerning ;(
    
    Bootstrapped and regression tested on x86.  Obviously fixes the testcase on
    riscv as well.
    
    Pushing to the trunk.
    
            PR rtl-optimization/116544
    gcc/
            * ext-dce.cc (ext_dce_process_uses): Fix thinko in promoted subreg
            handling.
    
    gcc/testsuite/
            * gcc.dg/torture/pr116544.c: New test.
diff mbox series

Patch

diff --git a/gcc/ext-dce.cc b/gcc/ext-dce.cc
index 4a2503f1831..2f3514ae797 100644
--- a/gcc/ext-dce.cc
+++ b/gcc/ext-dce.cc
@@ -846,7 +846,7 @@  ext_dce_process_uses (rtx_insn *insn, rtx obj,
 	    bitmap_set_bit (livenow, rn + 1);
 	  if (size > 16)
 	    bitmap_set_bit (livenow, rn + 2);
-	  if (size == 32)
+	  if (size >= 32)
 	    bitmap_set_bit (livenow, rn + 3);
 	  iter.skip_subrtxes ();
 	}
diff --git a/gcc/testsuite/gcc.dg/torture/pr116544.c b/gcc/testsuite/gcc.dg/torture/pr116544.c
new file mode 100644
index 00000000000..15f52fecb3b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr116544.c
@@ -0,0 +1,22 @@ 
+/* { dg-options "-fno-strict-aliasing -fwrapv" }
+/* { dg-do run { target longlong64 } } */
+
+extern void abort (void);
+long long a;
+signed char b[60];
+signed char c;
+long long d[60];
+int e[30];
+long long *f = d;
+static void g(long long *j, long k) { *j = k; }
+int main() {
+  d[5] = 0x100000000;
+  for (int h = 2; h < 7; h += 3)
+    for (int i = 0; i < (c || b[h]) + 10; i += 11)
+      e[2] = f[h];
+  g(&a, e[2]);
+  if (a != 0)
+    abort ();
+  return 0;
+}
+