From: Segher Boessenkool <segher@kernel.crashing.org>
Date: Wed, 13 Dec 2017 14:05:57 +0000 (+0100)
Subject: combine: Fix PR83393
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=2046f23f52d5ed4299f12e5f98a88491e4936c44;p=gcc.git

combine: Fix PR83393

In move_deaths we move a REG_DEAD note if the instruction combination
has extended the lifetime of a register so that the existing note is
no longer valid.  We find that note using reg_stat, but what that finds
can refer to a later insn.  If so, we cannot use the cached value.  This
patch implements that.


	PR rtl-optimization/83393
	* combine.c (move_deaths): If reg_stat points to a too new insn in
	last_death, do not use it: find the proper insn instead.

gcc/testsuite/
	PR rtl-optimization/83393
	* gcc.dg/pr83393.c: New testcase.

From-SVN: r255606
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9b4829d670a..5d992af7077 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2017-12-13  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	PR rtl-optimization/83393
+	* combine.c (move_deaths): If reg_stat points to a too new insn in
+	last_death, do not use it: find the proper insn instead.
+
 2017-12-12  Jeff Law  <law@redhat.com>
 
 	PR tree-optimization/83298
diff --git a/gcc/combine.c b/gcc/combine.c
index b6410c3afb0..eb737f64002 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -13880,7 +13880,7 @@ move_deaths (rtx x, rtx maybe_kill_insn, int from_luid, rtx_insn *to_insn,
 
       /* If we do not know where the register died, it may still die between
 	 FROM_LUID and TO_INSN.  If so, find it.  This is PR83304.  */
-      if (!where_dead)
+      if (!where_dead || DF_INSN_LUID (where_dead) >= DF_INSN_LUID (to_insn))
 	{
 	  rtx_insn *insn = prev_real_insn (to_insn);
 	  while (insn
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 7159ab9bf47..c5f1d44d2e9 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-12-13  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	PR rtl-optimization/83393
+	* gcc.dg/pr83393.c: New testcase.
+
 2017-12-13  Nathan Sidwell  <nathan@acm.org>
 
 	PR c++/15272
diff --git a/gcc/testsuite/gcc.dg/pr83393.c b/gcc/testsuite/gcc.dg/pr83393.c
new file mode 100644
index 00000000000..a9a6b338e0b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr83393.c
@@ -0,0 +1,38 @@
+/* PR rtl-optimization/83393 */
+/* { dg-do run } */
+/* { dg-options "-O2 -fno-forward-propagate -fno-tree-bit-ccp" } */
+
+typedef unsigned char u8;
+typedef unsigned short u16;
+typedef unsigned int u32;
+typedef unsigned long long u64;
+
+u32 a, d;
+u64 b;
+u8 c;
+
+static u64 __attribute__ ((noinline, noclone))
+foo (u16 f, u64 g)
+{
+  f <<= 15;
+  f *= d;
+  f -= g %= 44;
+  f <<= f <= g;
+  c = 255;
+  c >>= (u8) f == 0;
+  f *= g;
+  c -= ~c;
+  return f + a + b + f;
+}
+
+int
+main (void)
+{
+#if (__SIZEOF_LONG_LONG__ == 8 && __SIZEOF_INT__ == 4 \
+     && __SIZEOF_SHORT__ == 2 && __CHAR_BIT__ == 8)
+  u64 x = foo (3, 0xE6C0011BBA6DBD7LL);
+  if (x != 0x1f66e)
+    __builtin_abort ();
+#endif
+  return 0;
+}