[gcc r12-5106] [AArch64] Fix TBAA information when lowering NEON loads and stores to gimple

[Andre Simoes Dias Vieira <avieira@gcc.gnu.org>]

https://gcc.gnu.org/g:0f68560161deb000149a59931dfe5bca60af92d8

commit r12-5106-g0f68560161deb000149a59931dfe5bca60af92d8
Author: Andre Vieira <andre.simoesdiasvieira@arm.com>
Date:   Wed Nov 10 09:52:49 2021 +0000

    [AArch64] Fix TBAA information when lowering NEON loads and stores to gimple
    
    This patch fixes the wrong TBAA information when lowering NEON loads and stores
    to gimple that showed up when bootstrapping with UBSAN.
    
    gcc/ChangeLog:
    
            * config/aarch64/aarch64-builtins.c
            (aarch64_general_gimple_fold_builtin): Change pointer alignment and
            alias.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/aarch64/simd/lowering_tbaa.c: New test.

Diff:
---
 gcc/config/aarch64/aarch64-builtins.c              | 35 +++++++++++-----------
 .../gcc.target/aarch64/simd/lowering_tbaa.c        | 30 +++++++++++++++++++
 2 files changed, 47 insertions(+), 18 deletions(-)

diff --git a/gcc/config/aarch64/aarch64-builtins.c b/gcc/config/aarch64/aarch64-builtins.c
index 5053bf0f8fd..416b4fc2dea 100644
--- a/gcc/config/aarch64/aarch64-builtins.c
+++ b/gcc/config/aarch64/aarch64-builtins.c
@@ -2670,18 +2670,18 @@ aarch64_general_gimple_fold_builtin (unsigned int fcode, gcall *stmt,
 	      = get_mem_type_for_load_store(fcode);
 	    aarch64_simd_type_info simd_type
 	      = aarch64_simd_types[mem_type];
-	    tree elt_ptr_type = build_pointer_type (simd_type.eltype);
+	    tree elt_ptr_type = build_pointer_type_for_mode (simd_type.eltype,
+							     VOIDmode, true);
 	    tree zero = build_zero_cst (elt_ptr_type);
-	    gimple_seq stmts = NULL;
-	    tree base = gimple_convert (&stmts, elt_ptr_type,
-					args[0]);
-	    if (stmts)
-	      gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
+	    /* Use element type alignment.  */
+	    tree access_type
+	      = build_aligned_type (simd_type.itype,
+				    TYPE_ALIGN (simd_type.eltype));
 	    new_stmt
 	      = gimple_build_assign (gimple_get_lhs (stmt),
 				     fold_build2 (MEM_REF,
-						  simd_type.itype,
-						  base, zero));
+						  access_type,
+						  args[0], zero));
 	  }
 	break;
 
@@ -2692,18 +2692,17 @@ aarch64_general_gimple_fold_builtin (unsigned int fcode, gcall *stmt,
 	      = get_mem_type_for_load_store(fcode);
 	    aarch64_simd_type_info simd_type
 	      = aarch64_simd_types[mem_type];
-	    tree elt_ptr_type = build_pointer_type (simd_type.eltype);
+	    tree elt_ptr_type = build_pointer_type_for_mode (simd_type.eltype,
+							     VOIDmode, true);
 	    tree zero = build_zero_cst (elt_ptr_type);
-	    gimple_seq stmts = NULL;
-	    tree base = gimple_convert (&stmts, elt_ptr_type,
-					args[0]);
-	    if (stmts)
-	      gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
+	    /* Use element type alignment.  */
+	    tree access_type
+	      = build_aligned_type (simd_type.itype,
+				    TYPE_ALIGN (simd_type.eltype));
 	    new_stmt
-	      = gimple_build_assign (fold_build2 (MEM_REF,
-				     simd_type.itype,
-				     base,
-				     zero), args[1]);
+	      = gimple_build_assign (fold_build2 (MEM_REF, access_type,
+						  args[0], zero),
+				     args[1]);
 	  }
 	break;
 
diff --git a/gcc/testsuite/gcc.target/aarch64/simd/lowering_tbaa.c b/gcc/testsuite/gcc.target/aarch64/simd/lowering_tbaa.c
new file mode 100644
index 00000000000..eaeae21f19c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/simd/lowering_tbaa.c
@@ -0,0 +1,30 @@
+/* Tests the TBAA information of lowered AArch64 SIMD loads.  */
+/* { dg-do run } */
+/* { dg-options "-save-temps -O2" } */
+
+#include <arm_neon.h>
+
+void __attribute__((noipa))
+g (float *)
+{
+}
+
+int32x4_t __attribute__((noipa))
+f (void)
+{
+  float a[4] = { 1, 2, 3, 4 };
+  g (a);
+  a[0] = a[1] = a[2] = a[3] = 0;
+  void *volatile ptr = a;
+  return vld1q_s32 ((int32_t *) ptr);
+}
+
+int
+main (void)
+{
+  int32x4_t x = f ();
+  int32x4_t y = vdupq_n_s32 (0);
+  if (__builtin_memcmp (&x, &y, 16) != 0)
+    __builtin_abort ();
+  return 0;
+}