PR tree-optimization/92712

	* match.pd ((A * B) +- A -> (B +- 1) * A,
	A +- (A * B) -> (1 +- B) * A): Allow optimizing signed integers
	even when we don't know anything about range of A, but do know
	something about range of B and the simplification won't introduce
	new UB.

	* gcc.dg/tree-ssa/pr92712-1.c: New test.
	* gcc.dg/tree-ssa/pr92712-2.c: New test.
	* gcc.dg/tree-ssa/pr92712-3.c: New test.
	* gfortran.dg/loop_versioning_1.f90: Adjust expected number of
	likely to be innermost dimension messages.
	* gfortran.dg/loop_versioning_10.f90: Likewise.
	* gfortran.dg/loop_versioning_6.f90: Likewise.


git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@278894 138bc75d-0d04-0410-961f-82ee72b054a4

9 files changed, 179 insertions, 10 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0765ee2be12..9b324211554 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,4 +1,13 @@
-2019-12-02  Feng Xue <fxue@os.amperecomputing.com>
+2019-12-02  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/92712
+	* match.pd ((A * B) +- A -> (B +- 1) * A,
+	A +- (A * B) -> (1 +- B) * A): Allow optimizing signed integers
+	even when we don't know anything about range of A, but do know
+	something about range of B and the simplification won't introduce
+	new UB.
+
+2019-12-02  Feng Xue  <fxue@os.amperecomputing.com>
 
 	PR ipa/92133
 	* doc/invoke.texi (ipa-cp-max-recursive-depth): Document new option.
@@ -4543,7 +4552,7 @@
 	(lto_free_file_name_hash): New function.
 	* lto-streamer.h (lto_free_file_name_hash): New.
 
-2019-11-07  Feng Xue <fxue@os.amperecomputing.com>
+2019-11-07  Feng Xue  <fxue@os.amperecomputing.com>
 
 	PR tree-optimization/89134
 	* doc/invoke.texi (min-loop-cond-split-prob): Document new --params.
diff --git a/gcc/match.pd b/gcc/match.pd
index eabd01fc115..14f6a9d5078 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -2480,18 +2480,42 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
     (plusminus @0 (mult:c@3 @0 @2))
     (if ((!ANY_INTEGRAL_TYPE_P (type)
 	  || TYPE_OVERFLOW_WRAPS (type)
+	  /* For @0 + @0*@2 this transformation would introduce UB
+	     (where there was none before) for @0 in [-1,0] and @2 max.
+	     For @0 - @0*@2 this transformation would introduce UB
+	     for @0 0 and @2 in [min,min+1] or @0 -1 and @2 min+1.  */
 	  || (INTEGRAL_TYPE_P (type)
-	      && tree_expr_nonzero_p (@0)
-	      && expr_not_equal_to (@0, wi::minus_one (TYPE_PRECISION (type)))))
+	      && ((tree_expr_nonzero_p (@0)
+		   && expr_not_equal_to (@0,
+				wi::minus_one (TYPE_PRECISION (type))))
+		  || (plusminus == PLUS_EXPR
+		      ? expr_not_equal_to (@2,
+			    wi::max_value (TYPE_PRECISION (type), SIGNED))
+		      /* Let's ignore the @0 -1 and @2 min case.  */
+		      : (expr_not_equal_to (@2,
+			    wi::min_value (TYPE_PRECISION (type), SIGNED))
+			 && expr_not_equal_to (@2,
+				wi::min_value (TYPE_PRECISION (type), SIGNED)
+				+ 1))))))
 	 && single_use (@3))
      (mult (plusminus { build_one_cst (type); } @2) @0)))
    (simplify
     (plusminus (mult:c@3 @0 @2) @0)
     (if ((!ANY_INTEGRAL_TYPE_P (type)
 	  || TYPE_OVERFLOW_WRAPS (type)
+	  /* For @0*@2 + @0 this transformation would introduce UB
+	     (where there was none before) for @0 in [-1,0] and @2 max.
+	     For @0*@2 - @0 this transformation would introduce UB
+	     for @0 0 and @2 min.  */
 	  || (INTEGRAL_TYPE_P (type)
-	      && tree_expr_nonzero_p (@0)
-	      && expr_not_equal_to (@0, wi::minus_one (TYPE_PRECISION (type)))))
+	      && ((tree_expr_nonzero_p (@0)
+		   && (plusminus == MINUS_EXPR
+		       || expr_not_equal_to (@0,
+				wi::minus_one (TYPE_PRECISION (type)))))
+		  || expr_not_equal_to (@2,
+			(plusminus == PLUS_EXPR
+			 ? wi::max_value (TYPE_PRECISION (type), SIGNED)
+			 : wi::min_value (TYPE_PRECISION (type), SIGNED))))))
 	 && single_use (@3))
      (mult (plusminus @2 { build_one_cst (type); }) @0))))))
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index bb36544cfe4..12abe735bbf 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,14 @@
+2019-12-02  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/92712
+	* gcc.dg/tree-ssa/pr92712-1.c: New test.
+	* gcc.dg/tree-ssa/pr92712-2.c: New test.
+	* gcc.dg/tree-ssa/pr92712-3.c: New test.
+	* gfortran.dg/loop_versioning_1.f90: Adjust expected number of
+	likely to be innermost dimension messages.
+	* gfortran.dg/loop_versioning_10.f90: Likewise.
+	* gfortran.dg/loop_versioning_6.f90: Likewise.
+
 2019-12-02  Feng Xue  <fxue@os.amperecomputing.com>
 
 	PR ipa/92133
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr92712-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr92712-1.c
new file mode 100644
index 00000000000..c19ff5cf29c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr92712-1.c
@@ -0,0 +1,21 @@
+/* PR tree-optimization/92712 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump " = \[tv]_\[0-9]*\\\(D\\\) \\* \[tv]_\[0-9]*\\\(D\\\);" "optimized" } } */
+
+static int
+foo (int t, int v)
+{
+  int i, x = 0;
+  for (int i = 0; i < t; ++i)
+    x += v;
+  return x;
+}
+
+int
+bar (int t, int v)
+{
+  if (t < 0)
+    __builtin_unreachable ();
+  return foo (t, v);
+}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr92712-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr92712-2.c
new file mode 100644
index 00000000000..2710ff36cc1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr92712-2.c
@@ -0,0 +1,66 @@
+/* PR tree-optimization/92712 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-ipa-icf -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump-times " = \[tv]_\[0-9]*\\\(D\\\) \\* \[tv]_\[0-9]*\\\(D\\\);" 7 "optimized" } } */
+
+int
+f1 (int t, int v)
+{
+  int a = t - 1;
+  int b = a * v;
+  return b + v;
+}
+
+int
+f2 (int t, int v)
+{
+  int a = t - 1;
+  int b = a * v;
+  return v + b;
+}
+
+int
+f3 (int t, int v)
+{
+  int a = t + 1;
+  int b = a * v;
+  return b - v;
+}
+
+int
+f4 (int t, int v)
+{
+  int a = 1 - t;
+  int b = a * v;
+  return v - b;
+}
+
+int
+f5 (int t, int v)
+{
+  if (v == 0 || v == -1)
+    __builtin_unreachable ();
+  int a = t - 1U;
+  int b = a * v;
+  return b + v;
+}
+
+int
+f6 (int t, int v)
+{
+  if (v == 0 || v == -1)
+    __builtin_unreachable ();
+  int a = t - 1U;
+  int b = a * v;
+  return v + b;
+}
+
+int
+f7 (int t, int v)
+{
+  if (v == 0)
+    __builtin_unreachable ();
+  int a = t + 1U;
+  int b = a * v;
+  return b - v;
+}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr92712-3.c b/gcc/testsuite/gcc.dg/tree-ssa/pr92712-3.c
new file mode 100644
index 00000000000..27749a125a7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr92712-3.c
@@ -0,0 +1,36 @@
+/* PR tree-optimization/92712 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-ipa-icf -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump-not " = \[tv]_\[0-9]*\\\(D\\\) \\* \[tv]_\[0-9]*\\\(D\\\);" "optimized" } } */
+
+int
+f1 (int t, int v)
+{
+  int a = t - 1U;
+  int b = a * v;
+  return b + v;
+}
+
+int
+f2 (int t, int v)
+{
+  int a = t - 1U;
+  int b = a * v;
+  return v + b;
+}
+
+int
+f3 (int t, int v)
+{
+  int a = t + 1U;
+  int b = a * v;
+  return b - v;
+}
+
+int
+f4 (int t, int v)
+{
+  int a = 1U - t;
+  int b = a * v;
+  return v - b;
+}
diff --git a/gcc/testsuite/gfortran.dg/loop_versioning_1.f90 b/gcc/testsuite/gfortran.dg/loop_versioning_1.f90
index 144a193d708..e80f8920d00 100644
--- a/gcc/testsuite/gfortran.dg/loop_versioning_1.f90
+++ b/gcc/testsuite/gfortran.dg/loop_versioning_1.f90
@@ -23,6 +23,6 @@ subroutine f3(x, limit, step)
   end do
 end subroutine f3
 
-! { dg-final { scan-tree-dump-times {likely to be the innermost dimension} 2 "lversion" } }
+! { dg-final { scan-tree-dump-times {likely to be the innermost dimension} 1 "lversion" } }
 ! { dg-final { scan-tree-dump-times {want to version containing loop} 3 "lversion" } }
 ! { dg-final { scan-tree-dump-times {versioned this loop} 3 "lversion" } }
diff --git a/gcc/testsuite/gfortran.dg/loop_versioning_10.f90 b/gcc/testsuite/gfortran.dg/loop_versioning_10.f90
index 5803527bb3c..3d921d6c993 100644
--- a/gcc/testsuite/gfortran.dg/loop_versioning_10.f90
+++ b/gcc/testsuite/gfortran.dg/loop_versioning_10.f90
@@ -26,6 +26,6 @@ subroutine f4(x, i)
   end do
 end subroutine f4
 
-! { dg-final { scan-tree-dump-times {likely to be the innermost dimension} 6 "lversion" } }
+! { dg-final { scan-tree-dump-times {likely to be the innermost dimension} 4 "lversion" } }
 ! { dg-final { scan-tree-dump-times {want to version} 4 "lversion" } }
 ! { dg-final { scan-tree-dump-times {versioned} 4 "lversion" } }
diff --git a/gcc/testsuite/gfortran.dg/loop_versioning_6.f90 b/gcc/testsuite/gfortran.dg/loop_versioning_6.f90
index 450a79c1fdf..163d225cb49 100644
--- a/gcc/testsuite/gfortran.dg/loop_versioning_6.f90
+++ b/gcc/testsuite/gfortran.dg/loop_versioning_6.f90
@@ -89,5 +89,7 @@ subroutine f9(x, limit, step)
   end do
 end subroutine f9
 
-! { dg-final { scan-tree-dump-times {want to version containing loop} 9 "lversion" } }
-! { dg-final { scan-tree-dump-times {versioned this loop} 9 "lversion" } }
+! { dg-final { scan-tree-dump-times {want to version containing loop} 9 "lversion" { target lp64 } } }
+! { dg-final { scan-tree-dump-times {versioned this loop} 9 "lversion" { target lp64 } } }
+! { dg-final { scan-tree-dump-times {want to version containing loop} 8 "lversion" { target { ! lp64 } } } }
+! { dg-final { scan-tree-dump-times {versioned this loop} 8 "lversion" { target { ! lp64 } } } }