Check for matching CONST_VECTOR encodings [PR99929]

PR99929 is one of those “how did we get away with this for so long”
bugs: the equality routines weren't checking whether two variable-length
CONST_VECTORs had the same encoding.  This meant that:

   { 1, 0, 0, 0, 0, 0, ... }

would appear to be equal to:

   { 1, 0, 1, 0, 1, 0, ... }

since both are represented using the elements { 1, 0 }.

gcc/
	PR rtl-optimization/99929
	* rtl.h (same_vector_encodings_p): New function.
	* cse.c (exp_equiv_p): Check that CONST_VECTORs have the same encoding.
	* cselib.c (rtx_equal_for_cselib_1): Likewise.
	* jump.c (rtx_renumbered_equal_p): Likewise.
	* lra-constraints.c (operands_match_p): Likewise.
	* reload.c (operands_match_p): Likewise.
	* rtl.c (rtx_equal_p_cb, rtx_equal_p): Likewise.

gcc/testsuite/
	* gcc.target/aarch64/sve/pr99929_1.c: New file.
	* gcc.target/aarch64/sve/pr99929_2.c: Likewise.

1 files changed, 10 insertions, 0 deletions

diff --git a/gcc/rtl.c b/gcc/rtl.c
index 1aa794c..e4ae168 100644
--- a/gcc/rtl.c
+++ b/gcc/rtl.c
@@ -466,6 +466,11 @@ rtx_equal_p_cb (const_rtx x, const_rtx y, rtx_equal_p_callback_function cb)
     CASE_CONST_UNIQUE:
       return 0;
 
+    case CONST_VECTOR:
+      if (!same_vector_encodings_p (x, y))
+	return false;
+      break;
+
     case DEBUG_IMPLICIT_PTR:
       return DEBUG_IMPLICIT_PTR_DECL (x)
 	     == DEBUG_IMPLICIT_PTR_DECL (y);
@@ -608,6 +613,11 @@ rtx_equal_p (const_rtx x, const_rtx y)
     CASE_CONST_UNIQUE:
       return 0;
 
+    case CONST_VECTOR:
+      if (!same_vector_encodings_p (x, y))
+	return false;
+      break;
+
     case DEBUG_IMPLICIT_PTR:
       return DEBUG_IMPLICIT_PTR_DECL (x)
 	     == DEBUG_IMPLICIT_PTR_DECL (y);