From 1f272f8f90cb1fc0a0a9ba3723aad13ebfcc5f03 Mon Sep 17 00:00:00 2001
From: florian <florian@freepascal.org>
Date: Tue, 31 Aug 2021 21:24:28 +0200
Subject: [PATCH]   * we cannot do SSA during partial writes to arrays which
 span multiple registers, resolves #39325

---
 compiler/hlcgobj.pas    | 8 +++++++-
 tests/webtbs/tw39325.pp | 8 ++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 tests/webtbs/tw39325.pp

diff --git a/compiler/hlcgobj.pas b/compiler/hlcgobj.pas
index 54917bfeac..b961831bd5 100644
--- a/compiler/hlcgobj.pas
+++ b/compiler/hlcgobj.pas
@@ -688,7 +688,8 @@ implementation
        fmodule,
        verbose,defutil,paramgr,
        symtable,
-       nbas,ncon,nld,ncgrtti,pass_2,
+       nbas,ncon,nld,nmem,
+       ncgrtti,pass_2,
        cgobj,cutils,procinfo,
 {$ifdef x86}
        cgx86,
@@ -4652,6 +4653,11 @@ implementation
         inn,
         asn,isn:
           result := fen_norecurse_false;
+        vecn:
+          { we cannot do SSA during partial writes to arrays which span multiple registers, see also tw39325 }
+          if (tvecnode(n).left.location.loc in [LOC_CREGISTER,LOC_CFPUREGISTER,LOC_CMMXREGISTER,LOC_CMMREGISTER]) and
+            (tcgsize2size[reg_cgsize(tvecnode(n).left.location.register)]<>tvecnode(n).left.resultdef.size) then
+            result := fen_norecurse_false;
         else
           ;
       end;
diff --git a/tests/webtbs/tw39325.pp b/tests/webtbs/tw39325.pp
new file mode 100644
index 0000000000..b9821dedd0
--- /dev/null
+++ b/tests/webtbs/tw39325.pp
@@ -0,0 +1,8 @@
+{ %OPT=-Ooregvar }
+program testopt;
+var
+ar: array[0..1] of byte;
+begin
+ar[0] := 1;
+ar[1] := 2;
+end.