From: Pat Haugen <pthaugen@us.ibm.com>
Date: Thu, 10 Nov 2016 18:55:57 +0000 (+0000)
Subject: re PR rtl-optimization/78241 (wrong code with -funroll-loops)
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=8d34bfa865fb527b6a3569528656e2dc8af592e0;p=gcc.git

re PR rtl-optimization/78241 (wrong code with -funroll-loops)

	PR rtl-optimization/78241
	* loop-unroll.c (unroll_loop_runtime_iterations): Don't adjust 'niter', but
	emit initial peel copy if niter expr is not reliable.

	* gcc.dg/pr78241.c: New test.

From-SVN: r242047
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 66586e4e033..66ff3618c8e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2016-11-10  Pat Haugen  <pthaugen@us.ibm.com>
+
+	PR rtl-optimization/78241
+	* loop-unroll.c (unroll_loop_runtime_iterations): Don't adjust 'niter', but
+	emit initial peel copy if niter expr is not reliable.
+
 2016-11-10  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	* dwarf2cfi.c (dump_cfi_row): Add forward declaration.
diff --git a/gcc/loop-unroll.c b/gcc/loop-unroll.c
index 91118a310d0..760445e6448 100644
--- a/gcc/loop-unroll.c
+++ b/gcc/loop-unroll.c
@@ -918,9 +918,10 @@ unroll_loop_runtime_iterations (struct loop *loop)
   if (tmp != niter)
     emit_move_insn (niter, tmp);
 
-  /* For loops that exit at end, add one to niter to account for first pass
-     through loop body before reaching exit test. */
-  if (exit_at_end)
+  /* For loops that exit at end and whose number of iterations is reliable,
+     add one to niter to account for first pass through loop body before
+     reaching exit test. */
+  if (exit_at_end && !desc->noloop_assumptions)
     {
       niter = expand_simple_binop (desc->mode, PLUS,
 				   niter, const1_rtx,
@@ -946,7 +947,7 @@ unroll_loop_runtime_iterations (struct loop *loop)
 
   auto_sbitmap wont_exit (max_unroll + 2);
 
-  if (extra_zero_check)
+  if (extra_zero_check || desc->noloop_assumptions)
     {
       /* Peel the first copy of loop body.  Leave the exit test if the number
 	 of iterations is not reliable.  Also record the place of the extra zero
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index d522e24928c..b3f944221f5 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-11-10  Pat Haugen  <pthaugen@us.ibm.com>
+
+	PR rtl-optimization/78241
+	* gcc.dg/pr78241.c: New test.
+
 2016-11-10  Jakub Jelinek  <jakub@redhat.com>
 
 	* gfortran.dg/openmp-define-3.f90: Expect 201511 instead of
diff --git a/gcc/testsuite/gcc.dg/pr78241.c b/gcc/testsuite/gcc.dg/pr78241.c
new file mode 100644
index 00000000000..b99dfca2ba0
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr78241.c
@@ -0,0 +1,20 @@
+/* { dg-do run } */
+/* { dg-options "-Og -funroll-loops" } */
+
+static __attribute__((noinline, noclone)) unsigned
+foo (unsigned x)
+{
+  do
+    x++;
+  while (x <= 15);
+  return x;
+}
+
+int main ()
+{
+  unsigned x = foo (-2);
+  if (x != (unsigned)-1)
+    __builtin_abort();
+  return 0;
+}
+