re PR tree-optimization/69726 (Bogus warnings with -O3 -Wuninitialized because…

re PR tree-optimization/69726 (Bogus warnings with -O3 -Wuninitialized because dead code after if-conversion)

2016-02-10  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/69726
	* passes.def: Add DCE pass before late uninit.
	* match.pd: Add A ? B : (!A ? C : X) -> A ? B : C patterns to
	really fixup if-conversions job.

	* gcc.dg/uninit-22.c: New testcase.

From-SVN: r233267

gcc/ChangeLog

+2016-02-10  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/69726
+	* passes.def: Add DCE pass before late uninit.
+	* match.pd: Add A ? B : (!A ? C : X) -> A ? B : C patterns to
+	really fixup if-conversions job.
+
 2016-02-10  Wilco Dijkstra  <wdijkstr@arm.com>
 
 	* config/arm/arm.c (arm_cortex_a53_tune): Enable AES fusion.

gcc/match.pd

@@ -1717,6 +1717,29 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  (simplify
   (cnd @0 @1 (cnd @0 @2 @3))
   (cnd @0 @1 @3))
+ /* A ? B : (!A ? C : X) -> A ? B : C.  */
+ /* ???  This matches embedded conditions open-coded because genmatch
+    would generate matching code for conditions in separate stmts only.
+    The following is still important to merge then and else arm cases
+    from if-conversion.  */
+ (simplify
+  (cnd @0 @1 (cnd @2 @3 @4))
+  (if (COMPARISON_CLASS_P (@0)
+       && COMPARISON_CLASS_P (@2)
+       && invert_tree_comparison
+           (TREE_CODE (@0), HONOR_NANS (TREE_OPERAND (@0, 0))) == TREE_CODE (@2)
+       && operand_equal_p (TREE_OPERAND (@0, 0), TREE_OPERAND (@2, 0), 0)
+       && operand_equal_p (TREE_OPERAND (@0, 1), TREE_OPERAND (@2, 1), 0))
+   (cnd @0 @1 @3)))
+ (simplify
+  (cnd @0 (cnd @1 @2 @3) @4)
+  (if (COMPARISON_CLASS_P (@0)
+       && COMPARISON_CLASS_P (@1)
+       && invert_tree_comparison
+           (TREE_CODE (@0), HONOR_NANS (TREE_OPERAND (@0, 0))) == TREE_CODE (@1)
+       && operand_equal_p (TREE_OPERAND (@0, 0), TREE_OPERAND (@1, 0), 0)
+       && operand_equal_p (TREE_OPERAND (@0, 1), TREE_OPERAND (@1, 1), 0))
+   (cnd @0 @3 @4)))
 
  /* A ? B : B -> B.  */
  (simplify

gcc/passes.def

@@ -322,15 +322,11 @@ along with GCC; see the file COPYING3.  If not see
       NEXT_PASS (pass_fold_builtins);
       NEXT_PASS (pass_optimize_widening_mul);
       NEXT_PASS (pass_tail_calls);
-      /* FIXME: If DCE is not run before checking for uninitialized uses,
+      /* If DCE is not run before checking for uninitialized uses,
 	 we may get false warnings (e.g., testsuite/gcc.dg/uninit-5.c).
 	 However, this also causes us to misdiagnose cases that should be
-	 real warnings (e.g., testsuite/gcc.dg/pr18501.c).
-
-	 To fix the false positives in uninit-5.c, we would have to
-	 account for the predicates protecting the set and the use of each
-	 variable.  Using a representation like Gated Single Assignment
-	 may help.  */
+	 real warnings (e.g., testsuite/gcc.dg/pr18501.c).  */
+      NEXT_PASS (pass_dce);
       /* Split critical edges before late uninit warning to reduce the
          number of false positives from it.  */
       NEXT_PASS (pass_split_crit_edges);

gcc/testsuite/ChangeLog

+2016-02-10  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/69726
+	* gcc.dg/uninit-22.c: New testcase.
+
 2016-02-09  Andrew Pinski  <apinski@cavium.com>
 
 	PR tree-opt/69282

gcc/testsuite/gcc.dg/uninit-22.c

+/* { dg-do compile } */
+/* { dg-options "-O3 -Wuninitialized --param vect-max-version-for-alias-checks=20" } */
+
+#include <stdint.h>
+
+#define A1  2896 /* (1/sqrt(2))<<12 */
+#define A2  2217
+#define A3  3784
+#define A4 -5352
+
+#define IDCT_TRANSFORM(dest,s0,s1,s2,s3,s4,s5,s6,s7,d0,d1,d2,d3,d4,d5,d6,d7,munge,src) {\
+    const int a0 = (src)[s0] + (src)[s4]; \
+    const int a1 = (src)[s0] - (src)[s4]; \
+    const int a2 = (src)[s2] + (src)[s6]; \
+    const int a3 = (A1*((src)[s2] - (src)[s6])) >> 11; \
+    const int a4 = (src)[s5] + (src)[s3]; \
+    const int a5 = (src)[s5] - (src)[s3]; \
+    const int a6 = (src)[s1] + (src)[s7]; \
+    const int a7 = (src)[s1] - (src)[s7]; \
+    const int b0 = a4 + a6; \
+    const int b1 = (A3*(a5 + a7)) >> 11; \
+    const int b2 = ((A4*a5) >> 11) - b0 + b1; \
+    const int b3 = (A1*(a6 - a4) >> 11) - b2; \
+    const int b4 = ((A2*a7) >> 11) + b3 - b1; \
+    (dest)[d0] = munge(a0+a2   +b0); \
+    (dest)[d1] = munge(a1+a3-a2+b2); \
+    (dest)[d2] = munge(a1-a3+a2+b3); \
+    (dest)[d3] = munge(a0-a2   -b4); \
+    (dest)[d4] = munge(a0-a2   +b4); \
+    (dest)[d5] = munge(a1-a3+a2-b3); \
+    (dest)[d6] = munge(a1+a3-a2-b2); \
+    (dest)[d7] = munge(a0+a2   -b0); \
+}
+
+#define MUNGE_NONE(x) (x)
+#define IDCT_COL(dest,src) IDCT_TRANSFORM(dest,0,8,16,24,32,40,48,56,0,8,16,24,32,40,48,56,MUNGE_NONE,src)
+
+#define MUNGE_ROW(x) (((x) + 0x7F)>>8)
+#define IDCT_ROW(dest,src) IDCT_TRANSFORM(dest,0,1,2,3,4,5,6,7,0,1,2,3,4,5,6,7,MUNGE_ROW,src)
+
+static inline void bink_idct_col(int *dest, const int32_t *src)
+{
+    if ((src[8]|src[16]|src[24]|src[32]|src[40]|src[48]|src[56])==0) {
+        dest[0]  =
+        dest[8]  =
+        dest[16] =
+        dest[24] =
+        dest[32] =
+        dest[40] =
+        dest[48] =
+        dest[56] = src[0];
+    } else {
+        IDCT_COL(dest, src);
+    }
+}
+
+int bink_idct_put_c(uint8_t *dest, int linesize, int32_t *block)
+{
+    int i;
+    int temp[64];
+    for (i = 0; i < 8; i++)
+        bink_idct_col(&temp[i], &block[i]);
+    for (i = 0; i < 8; i++) {
+        IDCT_ROW( (&dest[i*linesize]), (&temp[8*i]) );
+    }
+
+    return 0;
+}
+