Add a testcase for GCC PR 23455, which lpre handles now. Add some

comments about why we're not getting other cases.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61032 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 4 deletions

diff --git a/lib/Target/README.txt b/lib/Target/README.txt
index c19fd9c122..381d0c3bec 100644
--- a/lib/Target/README.txt
+++ b/lib/Target/README.txt
@@ -1323,8 +1323,13 @@ for () {
 }
 *P = tmp;
 
+We now hoist the reload after the call (Transforms/GVN/lpre-call-wrap.ll), but
+we don't sink the store.  We need partially dead store sinking.
+
 //===---------------------------------------------------------------------===//
 
+[PHI TRANSLATE GEPs]
+
 GCC PR37166: Sinking of loads prevents SROA'ing the "g" struct on the stack
 leading to excess stack traffic. This could be handled by GVN with some crazy
 symbolic phi translation.  The code we get looks like (g is on the stack):
@@ -1350,10 +1355,11 @@ There are many load PRE testcases in testsuite/gcc.dg/tree-ssa/loadpre* in the
 GCC testsuite.  There are many pre testcases as ssa-pre-*.c
 
 Other simple load PRE cases:
-http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35287
-http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34677 (licm does this)
-http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29789 (SPEC2K6)
-http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23455
+http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35287 [LPRE crit edge splitting]
+
+http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34677 (licm does this, LPRE crit edge)
+  llvm-gcc t2.c -S -o - -O0 -emit-llvm | llvm-as | opt -mem2reg -simplifycfg -gvn | llvm-dis
+
 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14705
 
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