From 0bb37e80bb786e11cb7aa2d23b7d68bb0357fc15 Mon Sep 17 00:00:00 2001
From: Eric Botcazou <ebotcazou@adacore.com>
Date: Mon, 19 Apr 2021 10:13:36 +0200
Subject: [PATCH] Fix another -freorder-blocks-and-partition glitch with
Windows SEH
Since GCC 8, the -freorder-blocks-and-partition pass can split a function
into hot and cold parts, thus generating 2 FDEs for a single function in
DWARF for exception purposes and doing an equivalent trick for Windows SEH.
Now the Windows system unwinder does not support arbitrarily large frames
and there is even a hard limit on the encoding of the CFI, which changes
the stack allocation strategy when it is topped and which must be reflected
everywhere.
gcc/
* config/i386/winnt.c (i386_pe_seh_cold_init): Properly deal with
frames larger than the SEH maximum frame size.
gcc/testsuite/
* gnat.dg/opt92.adb: New test.
---
gcc/config/i386/winnt.c | 16 ++++++++------
gcc/testsuite/gnat.dg/opt92.adb | 38 +++++++++++++++++++++++++++++++++
2 files changed, 47 insertions(+), 7 deletions(-)
create mode 100644 gcc/testsuite/gnat.dg/opt92.adb
diff --git a/gcc/config/i386/winnt.c b/gcc/config/i386/winnt.c
index cc1219652943..b66263ad2438 100644
--- a/gcc/config/i386/winnt.c
+++ b/gcc/config/i386/winnt.c
@@ -921,15 +921,17 @@ i386_pe_seh_cold_init (FILE *f, const char *name)
/* In the normal case, the frame pointer is near the bottom of the frame
so we can do the full stack allocation and set it afterwards. There
- is an exception when the function accesses prior frames so, in this
- case, we need to pre-allocate a small chunk before setting it. */
- if (crtl->accesses_prior_frames)
- alloc_offset = seh->cfa_offset;
- else
+ is an exception if the function overflows the SEH maximum frame size
+ or accesses prior frames so, in this case, we need to pre-allocate a
+ small chunk of stack before setting it. */
+ offset = seh->sp_offset - INCOMING_FRAME_SP_OFFSET;
+ if (offset < SEH_MAX_FRAME_SIZE && !crtl->accesses_prior_frames)
alloc_offset = seh->sp_offset;
+ else
+ alloc_offset = MIN (seh->cfa_offset + 240, seh->sp_offset);
offset = alloc_offset - INCOMING_FRAME_SP_OFFSET;
- if (offset > 0 && offset < SEH_MAX_FRAME_SIZE)
+ if (offset > 0)
fprintf (f, "\t.seh_stackalloc\t" HOST_WIDE_INT_PRINT_DEC "\n", offset);
for (int regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
@@ -958,7 +960,7 @@ i386_pe_seh_cold_init (FILE *f, const char *name)
fprintf (f, ", " HOST_WIDE_INT_PRINT_DEC "\n", offset);
}
- if (crtl->accesses_prior_frames)
+ if (alloc_offset != seh->sp_offset)
{
offset = seh->sp_offset - alloc_offset;
if (offset > 0 && offset < SEH_MAX_FRAME_SIZE)
diff --git a/gcc/testsuite/gnat.dg/opt92.adb b/gcc/testsuite/gnat.dg/opt92.adb
new file mode 100644
index 000000000000..f6eb6a034ec5
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/opt92.adb
@@ -0,0 +1,38 @@
+-- { dg-do compile { target { lp64 || llp64 } } }
+-- { dg-options "-O2 -gnatws" }
+
+procedure Main is
+
+ subtype Int64 is Long_Long_Integer;
+
+ type Arr is array (Int64 range <>) of Boolean;
+
+ Pow : constant := 10;
+
+ procedure Compute (B : in out Arr) is
+ Factor : Int64 := 3;
+ Num : Int64;
+ begin
+ while Factor <= 10 ** (Pow / 2) loop
+ Num := Factor;
+ while Num < 10 ** Pow loop
+ if B (Num) then
+ Factor := Num;
+ exit;
+ end if;
+ Num := Num + 2;
+ end loop;
+ Num := Factor * Factor;
+ while Num < 10 ** Pow loop
+ B (Num) := False;
+ Num := Num + Factor * 2;
+ end loop;
+ Factor := Factor + 2;
+ end loop;
+ end;
+
+ B : Arr (1 .. 10 ** Pow) := (others => True);
+
+begin
+ Compute (B);
+end;
--
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