[GCC-10,backport] arm: _Generic feature failing with ICE for -O0 (pr97205).

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  • [GCC-10,backport] arm: _Generic feature failing with ICE for -O0 (pr97205).
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Commit Message

Jeff Law via Gcc-patches April 30, 2021, 3:18 p.m.
Hi,

This is a backport to GCC-10 to fix PR97205, patch applies
cleanly on the branch.

Regression tested and found no issues.

Ok for GCC-10 backport?

Regards,
Srinath.

    This makes sure that stack allocated SSA_NAMEs are
    at least MODE_ALIGNED.  Also increase the MEM_ALIGN
    for the corresponding rtl objects.

    gcc:
    2020-11-03  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        PR target/97205
        * cfgexpand.c (align_local_variable): Make SSA_NAMEs
        at least MODE_ALIGNED.
        (expand_one_stack_var_at): Increase MEM_ALIGN for SSA_NAMEs.

    gcc/testsuite:
    2020-11-03  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        PR target/97205
        * gcc.c-torture/compile/pr97205.c: New test.

    (cherry picked from commit 23ac7a009ecfeec3eab79136abed8aac9768b458)


###############     Attachment also inlined for ease of reply    ###############
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index bf4f194ed993134109cc21be9cb0ed8a5c170824..4fef5d6ebf420ce4d6f59606ecd064f45ae59065 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -366,7 +366,15 @@ align_local_variable (tree decl, bool really_expand)
   unsigned int align;
 
   if (TREE_CODE (decl) == SSA_NAME)
-    align = TYPE_ALIGN (TREE_TYPE (decl));
+    {
+      tree type = TREE_TYPE (decl);
+      machine_mode mode = TYPE_MODE (type);
+
+      align = TYPE_ALIGN (type);
+      if (mode != BLKmode
+	  && align < GET_MODE_ALIGNMENT (mode))
+	align = GET_MODE_ALIGNMENT (mode);
+    }
   else
     {
       align = LOCAL_DECL_ALIGNMENT (decl);
@@ -999,20 +1007,21 @@ expand_one_stack_var_at (tree decl, rtx base, unsigned base_align,
   x = plus_constant (Pmode, base, offset);
   x = gen_rtx_MEM (TREE_CODE (decl) == SSA_NAME
 		   ? TYPE_MODE (TREE_TYPE (decl))
-		   : DECL_MODE (SSAVAR (decl)), x);
+		   : DECL_MODE (decl), x);
+
+  /* Set alignment we actually gave this decl if it isn't an SSA name.
+     If it is we generate stack slots only accidentally so it isn't as
+     important, we'll simply set the alignment directly on the MEM.  */
+
+  if (base == virtual_stack_vars_rtx)
+    offset -= frame_phase;
+  align = known_alignment (offset);
+  align *= BITS_PER_UNIT;
+  if (align == 0 || align > base_align)
+    align = base_align;
 
   if (TREE_CODE (decl) != SSA_NAME)
     {
-      /* Set alignment we actually gave this decl if it isn't an SSA name.
-         If it is we generate stack slots only accidentally so it isn't as
-	 important, we'll simply use the alignment that is already set.  */
-      if (base == virtual_stack_vars_rtx)
-	offset -= frame_phase;
-      align = known_alignment (offset);
-      align *= BITS_PER_UNIT;
-      if (align == 0 || align > base_align)
-	align = base_align;
-
       /* One would think that we could assert that we're not decreasing
 	 alignment here, but (at least) the i386 port does exactly this
 	 via the MINIMUM_ALIGNMENT hook.  */
@@ -1022,6 +1031,8 @@ expand_one_stack_var_at (tree decl, rtx base, unsigned base_align,
     }
 
   set_rtl (decl, x);
+
+  set_mem_align (x, align);
 }
 
 class stack_vars_data
@@ -1327,13 +1338,11 @@ expand_one_stack_var_1 (tree var)
     {
       tree type = TREE_TYPE (var);
       size = tree_to_poly_uint64 (TYPE_SIZE_UNIT (type));
-      byte_align = TYPE_ALIGN_UNIT (type);
     }
   else
-    {
-      size = tree_to_poly_uint64 (DECL_SIZE_UNIT (var));
-      byte_align = align_local_variable (var, true);
-    }
+    size = tree_to_poly_uint64 (DECL_SIZE_UNIT (var));
+
+  byte_align = align_local_variable (var, true);
 
   /* We handle highly aligned variables in expand_stack_vars.  */
   gcc_assert (byte_align * BITS_PER_UNIT <= MAX_SUPPORTED_STACK_ALIGNMENT);
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr97205.c b/gcc/testsuite/gcc.c-torture/compile/pr97205.c
new file mode 100644
index 0000000000000000000000000000000000000000..6600011fcf84660edcba8d968c78ee6aaa0aa923
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr97205.c
@@ -0,0 +1,7 @@
+int a;
+typedef __attribute__((aligned(2))) int x;
+int f ()
+{
+  x b = a;
+  return b;
+}

Patch

diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index bf4f194ed993134109cc21be9cb0ed8a5c170824..4fef5d6ebf420ce4d6f59606ecd064f45ae59065 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -366,7 +366,15 @@  align_local_variable (tree decl, bool really_expand)
   unsigned int align;
 
   if (TREE_CODE (decl) == SSA_NAME)
-    align = TYPE_ALIGN (TREE_TYPE (decl));
+    {
+      tree type = TREE_TYPE (decl);
+      machine_mode mode = TYPE_MODE (type);
+
+      align = TYPE_ALIGN (type);
+      if (mode != BLKmode
+	  && align < GET_MODE_ALIGNMENT (mode))
+	align = GET_MODE_ALIGNMENT (mode);
+    }
   else
     {
       align = LOCAL_DECL_ALIGNMENT (decl);
@@ -999,20 +1007,21 @@  expand_one_stack_var_at (tree decl, rtx base, unsigned base_align,
   x = plus_constant (Pmode, base, offset);
   x = gen_rtx_MEM (TREE_CODE (decl) == SSA_NAME
 		   ? TYPE_MODE (TREE_TYPE (decl))
-		   : DECL_MODE (SSAVAR (decl)), x);
+		   : DECL_MODE (decl), x);
+
+  /* Set alignment we actually gave this decl if it isn't an SSA name.
+     If it is we generate stack slots only accidentally so it isn't as
+     important, we'll simply set the alignment directly on the MEM.  */
+
+  if (base == virtual_stack_vars_rtx)
+    offset -= frame_phase;
+  align = known_alignment (offset);
+  align *= BITS_PER_UNIT;
+  if (align == 0 || align > base_align)
+    align = base_align;
 
   if (TREE_CODE (decl) != SSA_NAME)
     {
-      /* Set alignment we actually gave this decl if it isn't an SSA name.
-         If it is we generate stack slots only accidentally so it isn't as
-	 important, we'll simply use the alignment that is already set.  */
-      if (base == virtual_stack_vars_rtx)
-	offset -= frame_phase;
-      align = known_alignment (offset);
-      align *= BITS_PER_UNIT;
-      if (align == 0 || align > base_align)
-	align = base_align;
-
       /* One would think that we could assert that we're not decreasing
 	 alignment here, but (at least) the i386 port does exactly this
 	 via the MINIMUM_ALIGNMENT hook.  */
@@ -1022,6 +1031,8 @@  expand_one_stack_var_at (tree decl, rtx base, unsigned base_align,
     }
 
   set_rtl (decl, x);
+
+  set_mem_align (x, align);
 }
 
 class stack_vars_data
@@ -1327,13 +1338,11 @@  expand_one_stack_var_1 (tree var)
     {
       tree type = TREE_TYPE (var);
       size = tree_to_poly_uint64 (TYPE_SIZE_UNIT (type));
-      byte_align = TYPE_ALIGN_UNIT (type);
     }
   else
-    {
-      size = tree_to_poly_uint64 (DECL_SIZE_UNIT (var));
-      byte_align = align_local_variable (var, true);
-    }
+    size = tree_to_poly_uint64 (DECL_SIZE_UNIT (var));
+
+  byte_align = align_local_variable (var, true);
 
   /* We handle highly aligned variables in expand_stack_vars.  */
   gcc_assert (byte_align * BITS_PER_UNIT <= MAX_SUPPORTED_STACK_ALIGNMENT);
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr97205.c b/gcc/testsuite/gcc.c-torture/compile/pr97205.c
new file mode 100644
index 0000000000000000000000000000000000000000..6600011fcf84660edcba8d968c78ee6aaa0aa923
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr97205.c
@@ -0,0 +1,7 @@ 
+int a;
+typedef __attribute__((aligned(2))) int x;
+int f ()
+{
+  x b = a;
+  return b;
+}