Re: [PATCH] Fix PR middle-end/86705

[Jozef Lawrynowicz <jozef dot l at mittosystems dot com>]

On 30/07/18 14:29, Richard Biener wrote:
> On Sun, Jul 29, 2018 at 6:27 PM Jozef Lawrynowicz
> <jozef.l@mittosystems.com> wrote:
> > pr45678-2.c ICEs for msp430-elf with -mlarge, because an alignment of
> > POINTER_SIZE is attempted. POINTER_SIZE with -mlarge is 20-bits, so further
> > code in the middle-end that expects this to be a power or 2 causes odd
> > alignments to be set, in this case eventually resulting in an ICE.
> >
> > The test ICEs on gcc-7-branch, gcc-8-branch, and current trunk. It
> > successfully builds on gcc-6-branch.
> > The failure is caused by r235172.
> >
> > Successfully bootstrapped and regtested the attached patch for
> > x86-64-pc-linux-gnu, and msp430-elf with -mlarge, on trunk.
> >
> > Ok for gcc-7-branch, gcc-8-branch and trunk?
> I wonder if most (if not all) places you touch want to use
> get_mode_alignment (Pmode) instead?  (or ptr_mode)
>
> Anyhow, the patch is otherwise obvious though factoring
> the thing might be nice (thus my suggestion above...)
>
> Richard.

Thanks for the suggestion, using GET_MODE_ALIGNMENT does seem like a neater
idea.
After retesting, I went ahead and committed the below patch onto trunk, will
backport to gcc-7/8-branch later.

diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index d6e3c38..7353d5d 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -1257,10 +1257,10 @@ set_parm_rtl (tree parm, rtx x)
 	 allocate it, which means that in-frame portion is just a
 	 pointer.  ??? We've got a pseudo for sure here, do we
 	 actually dynamically allocate its spilling area if needed?
-	 ??? Isn't it a problem when POINTER_SIZE also exceeds
-	 MAX_SUPPORTED_STACK_ALIGNMENT, as on cris and lm32?  */
+	 ??? Isn't it a problem when Pmode alignment also exceeds
+	 MAX_SUPPORTED_STACK_ALIGNMENT, as can happen on cris and lm32?  */
       if (align > MAX_SUPPORTED_STACK_ALIGNMENT)
-	align = POINTER_SIZE;
+	align = GET_MODE_ALIGNMENT (Pmode);
 
       record_alignment_for_reg_var (align);
     }
@@ -1381,7 +1381,7 @@ expand_one_ssa_partition (tree var)
   /* If the variable alignment is very large we'll dynamicaly allocate
      it, which means that in-frame portion is just a pointer.  */
   if (align > MAX_SUPPORTED_STACK_ALIGNMENT)
-    align = POINTER_SIZE;
+    align = GET_MODE_ALIGNMENT (Pmode);
 
   record_alignment_for_reg_var (align);
 
@@ -1608,7 +1608,7 @@ expand_one_var (tree var, bool toplevel, bool really_expand)
       /* If the variable alignment is very large we'll dynamicaly allocate
 	 it, which means that in-frame portion is just a pointer.  */
       if (align > MAX_SUPPORTED_STACK_ALIGNMENT)
-	align = POINTER_SIZE;
+	align = GET_MODE_ALIGNMENT (Pmode);
     }
 
   record_alignment_for_reg_var (align);