[gcc/devel/jlaw/pr71336] Daniel's patch for pr71336

[Jeff Law]

https://gcc.gnu.org/g:28132c5bbd86887afc7b41175ed3d0dfe579d750

commit 28132c5bbd86887afc7b41175ed3d0dfe579d750
Author: Jeff Law <jeffrey.law@oss.qualcomm.com>
Date:   Tue Mar 17 11:01:23 2026 -0600

    Daniel's patch for pr71336

Diff:
---
 gcc/match.pd                              | 38 ++++++++++++++++++++
 gcc/testsuite/gcc.dg/tree-ssa/pr71336-2.c | 59 +++++++++++++++++++++++++++++++
 gcc/testsuite/gcc.dg/tree-ssa/pr71336.c   | 20 +++++++++++
 3 files changed, 117 insertions(+)

diff --git a/gcc/match.pd b/gcc/match.pd
index 1d6428bf7e53..73bf697997aa 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -5195,6 +5195,44 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
        && expr_no_side_effects_p (@2))
        (op (mult (convert:type @0) @2) @1))))
 
+/* PR71336:
+   zero_one != 0 ? CST1 : CST2 -> ((typeof (CST2))zero_one * diff) + CST2,
+   where CST1 > CST2 and diff = CST1 - CST2.
+
+   Includes the "zero_one == 0 ? (...)" variant too.  */
+(for cmp (ne eq)
+ (simplify
+  (cond (cmp zero_one_valued_p@0 integer_zerop) INTEGER_CST@1 INTEGER_CST@2)
+  (with {
+    unsigned HOST_WIDE_INT diff = 0;
+
+    if (tree_int_cst_sgn (@1) > 0 && tree_int_cst_sgn (@2) > 0
+	&& tree_fits_uhwi_p (@1) && tree_fits_uhwi_p (@2))
+     {
+	if (cmp == NE_EXPR
+	    && wi::gtu_p (wi::to_wide (@1), wi::to_wide (@2)))
+	  diff = tree_to_uhwi (@1) - tree_to_uhwi (@2);
+
+	if (cmp == EQ_EXPR
+	    && wi::gtu_p (wi::to_wide (@2), wi::to_wide (@1)))
+	  diff = tree_to_uhwi (@2) - tree_to_uhwi (@1);
+     }
+   }
+   (if (cmp == NE_EXPR
+	&& INTEGRAL_TYPE_P (type)
+	&& TYPE_PRECISION (type) <= BITS_PER_WORD
+	&& INTEGRAL_TYPE_P (TREE_TYPE (@0))
+	&& diff > 0)
+     (plus (mult (convert:type @0) { build_int_cst (type, diff); })
+	    @2)
+    (if (cmp == EQ_EXPR
+	 && INTEGRAL_TYPE_P (type)
+	 && TYPE_PRECISION (type) <= BITS_PER_WORD
+	 && INTEGRAL_TYPE_P (TREE_TYPE (@0))
+	 && diff > 0)
+      (plus (mult (convert:type @0) { build_int_cst (type, diff); })
+	     @1))))))
+
 /* ?: Value replacement. */
 /* a == 0 ? b : b + a  -> b + a */
 (for op (plus bit_ior bit_xor)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr71336-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr71336-2.c
new file mode 100644
index 000000000000..da44489d3e4c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr71336-2.c
@@ -0,0 +1,59 @@
+/* { dg-do run } */
+/* { dg-options "-O1" } */
+
+/* Macro adapted from builtin-object-size-common.h  */
+#define FAIL() \
+  do { \
+    __builtin_printf ("Failure at line: %d\n", __LINE__);     \
+    abort();						      \
+  } while (0)
+
+void abort(void);
+
+int test (int a) {
+    return a & 1 ? 7 : 3;
+}
+
+int test2 (int a) {
+    return a & 1 ? 3 : 7;
+}
+
+int test3 (int a) {
+    return (a & 1) == 0 ? 3 : 7;
+}
+
+int test4 (int a) {
+    return (a & 1) == 0 ? 7 : 3;
+}
+
+int main (void) {
+  if (test (0) != 3)
+    FAIL ();
+  if (test (1) != 7)
+    FAIL ();
+  if (test (3) != 7)
+    FAIL ();
+
+  if (test2 (0) != 7)
+    FAIL ();
+  if (test2 (1) != 3)
+    FAIL ();
+  if (test2 (3) != 3)
+    FAIL ();
+
+  if (test3 (0) != 3)
+    FAIL ();
+  if (test3 (1) != 7)
+    FAIL ();
+  if (test3 (2) != 3)
+    FAIL ();
+
+  if (test4 (0) != 7)
+    FAIL ();
+  if (test4 (1) != 3)
+    FAIL ();
+  if (test4 (2) != 7)
+    FAIL ();
+
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr71336.c b/gcc/testsuite/gcc.dg/tree-ssa/pr71336.c
new file mode 100644
index 000000000000..fb643bf1eb35
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr71336.c
@@ -0,0 +1,20 @@
+/* { dg-additional-options -O1 } */
+/* { dg-additional-options -fdump-tree-gimple } */
+
+int test (int a) {
+    return a & 1 ? 7 : 3;
+}
+
+int test2 (int a) {
+    return (a & 1) == 0 ? 3 : 7;
+}
+
+int test3 (int a) {
+    return a & 1 ? 17 : 3;
+}
+
+int test4 (int a) {
+    return (a & 1) == 0 ? 3 : 17;
+}
+
+/* { dg-final { scan-tree-dump-times " goto " 0 gimple } } */