match.pd: Simplify X ? C : 0 where C is a power of 2 and X tests a single bit.

gcc:
* match.pd: Simplify X ? C : 0 where C is a power of 2 and
X tests a single bit.

gcc/testsuite:
* gcc.dg/fold-and-lshift.c, gcc.dg/fold-and-rshift-1.c,
gcc.dg/fold-and-rshift-2.c: New testcases.

From-SVN: r243255

6 files changed, 134 insertions, 1 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9488b0f..2ba0302 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2016-12-05  Paolo Bonzini  <bonzini@gnu.org>
+
+	* match.pd: Simplify X ? C : 0 where C is a power of 2 and
+	X tests a single bit.
+
 2016-12-05  Nathan Sidwell  <nathan@acm.org>
 
 	* diagnostic.c (diagnostic_check_max_errors): New, broken out of ...
@@ -25,7 +30,7 @@
 	* config/arc/arc.md (ls_gd_load): Remove unused pattern.
 	(tls_gd_dispatch): Likewise.
 
-2016-12-025  Andre Vieira  <andre.simoesdiasvieira@arm.com>
+2016-12-05  Andre Vieira  <andre.simoesdiasvieira@arm.com>
 
 	* config/arm/arm.c (TARGET_ASM_INIT_SECTIONS): Fix wrong undef
 	location.
diff --git a/gcc/match.pd b/gcc/match.pd
index dbb9103..1fe003b 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -2737,6 +2737,21 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
   (cmp (bit_and@2 @0 integer_pow2p@1) @1)
   (icmp @2 { build_zero_cst (TREE_TYPE (@0)); })))
  
+/* If we have (A & C) != 0 ? D : 0 where C and D are powers of 2,
+   convert this into a shift followed by ANDing with D.  */
+(simplify
+ (cond
+  (ne (bit_and @0 integer_pow2p@1) integer_zerop)
+  integer_pow2p@2 integer_zerop)
+ (with {
+    int shift = wi::exact_log2 (@2) - wi::exact_log2 (@1);
+  }
+  (if (shift > 0)
+   (bit_and
+    (lshift (convert @0) { build_int_cst (integer_type_node, shift); }) @2)
+   (bit_and
+    (convert (rshift @0 { build_int_cst (integer_type_node, -shift); })) @2))))
+
 /* If we have (A & C) != 0 where C is the sign bit of A, convert
    this into A < 0.  Similarly for (A & C) == 0 into A >= 0.  */
 (for cmp (eq ne)
@@ -2751,6 +2766,19 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
    (with { tree stype = signed_type_for (TREE_TYPE (@0)); }
     (ncmp (convert:stype @0) { build_zero_cst (stype); })))))
 
+/* If we have A < 0 ? C : 0 where C is a power of 2, convert
+   this into a right shift followed by ANDing with C.  */
+(simplify
+ (cond
+  (lt @0 integer_zerop)
+  integer_pow2p@1 integer_zerop)
+ (with {
+    int shift = element_precision (@0) - wi::exact_log2 (@1) - 1;
+  }
+  (bit_and
+   (convert (rshift @0 { build_int_cst (integer_type_node, shift); }))
+   @1)))
+
 /* When the addresses are not directly of decls compare base and offset.
    This implements some remaining parts of fold_comparison address
    comparisons but still no complete part of it.  Still it is good
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c40ffd6..d9edb52 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-12-05  Paolo Bonzini  <bonzini@gnu.org>
+
+	* gcc.dg/fold-and-lshift.c, gcc.dg/fold-and-rshift-1.c,
+	gcc.dg/fold-and-rshift-2.c: New testcases.
+
 2016-12-05  Nathan Sidwell  <nathan@acm.org>
 
 	* c-c++-common/fmax_errors.c: Check notes after last error are
diff --git a/gcc/testsuite/gcc.dg/fold-and-lshift.c b/gcc/testsuite/gcc.dg/fold-and-lshift.c
new file mode 100644
index 0000000..2905095
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/fold-and-lshift.c
@@ -0,0 +1,35 @@
+/* { dg-do compile } */

+/* { dg-options "-O -fdump-tree-original" } */

+

+int f(int x)

+{

+	return (x << 2) & 128;

+}

+

+int g(int x)

+{

+	return !!(x & 32) << 7;

+}

+

+int h(int x)

+{

+	return ((x >> 5) & 1) << 7;

+}

+

+int i(int x)

+{

+	return (x & 32) >> 5 << 7;

+}

+

+int j(int x)

+{

+	return ((x >> 5) & 1) ? 128 : 0;

+}

+

+int k(int x)

+{

+	return (x & 32) ? 128 : 0;

+}

+

+/* { dg-final { scan-tree-dump-not " \\? " "original" } } */

+/* { dg-final { scan-assembler-not "sarl" { target i?86-*-* x86_64-*-* } } }" */

diff --git a/gcc/testsuite/gcc.dg/fold-and-rshift-1.c b/gcc/testsuite/gcc.dg/fold-and-rshift-1.c
new file mode 100644
index 0000000..11c13d5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/fold-and-rshift-1.c
@@ -0,0 +1,35 @@
+/* { dg-do compile } */

+/* { dg-options "-O -fdump-tree-original" } */

+

+int f(int x)

+{

+	return (x >> 2) & 128;

+}

+

+int g(int x)

+{

+	return !!(x & 512) << 7;

+}

+

+int h(int x)

+{

+	return ((x >> 9) & 1) << 7;

+}

+

+int i(int x)

+{

+	return (x & 512) >> 9 << 7;

+}

+

+int j(int x)

+{

+	return ((x >> 9) & 1) ? 128 : 0;

+}

+

+int k(int x)

+{

+	return (x & 512) ? 128 : 0;

+}

+

+/* { dg-final { scan-tree-dump-not " \\? " "original" } } */

+/* { dg-final { scan-assembler-not "sall" { target i?86-*-* x86_64-*-* } } }" */

diff --git a/gcc/testsuite/gcc.dg/fold-and-rshift-2.c b/gcc/testsuite/gcc.dg/fold-and-rshift-2.c
new file mode 100644
index 0000000..f88d48d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/fold-and-rshift-2.c
@@ -0,0 +1,25 @@
+/* { dg-do compile } */

+/* { dg-options "-O -fdump-tree-original" } */

+

+unsigned f(unsigned x)

+{

+	return (x >> 29) & 32;

+}

+

+unsigned g(unsigned x)

+{

+	return !!(x & 0x80000000) << 5;

+}

+

+unsigned j(unsigned x)

+{

+	return ((x >> 31) & 1) ? 32 : 0;

+}

+

+unsigned k(unsigned x)

+{

+	return (x & 0x80000000) ? 32 : 0;

+}

+

+/* { dg-final { scan-tree-dump-not " \\? " "original" } } */

+/* { dg-final { scan-assembler-not "sall" { target i?86-*-* x86_64-*-* } } }" */