From f2c882496322c0d37dd22d5ad102dee17eda2842 Mon Sep 17 00:00:00 2001
From: yury <jura@cp-lab.com>
Date: Wed, 16 Sep 2015 13:52:15 +0000
Subject: [PATCH] * ARM: Do not use R9 as a fixed GOT register.

git-svn-id: trunk@31712 -
---
 compiler/arm/cgcpu.pas | 21 ++++++++++++++++-----
 compiler/arm/cpupi.pas |  2 +-
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/compiler/arm/cgcpu.pas b/compiler/arm/cgcpu.pas
index 1255d4a221..96f59d7afc 100644
--- a/compiler/arm/cgcpu.pas
+++ b/compiler/arm/cgcpu.pas
@@ -2344,20 +2344,31 @@ unit cgcpu;
            (pi_needs_got in current_procinfo.flags) and
            (tf_pic_uses_got in target_info.flags) then
           begin
-            a_reg_alloc(list,current_procinfo.got);  // Alloc PIC register
-            if getsupreg(current_procinfo.got) < first_int_imreg then
-              include(rg[R_INTREGISTER].used_in_proc,getsupreg(current_procinfo.got));
             reference_reset(ref,4);
             current_asmdata.getglobaldatalabel(l);
             cg.a_label(current_procinfo.aktlocaldata,l);
             ref.symbol:=l;
             ref.base:=NR_PC;
             ref.symboldata:=current_procinfo.aktlocaldata.last;
-            list.concat(Taicpu.op_reg_ref(A_LDR,current_procinfo.got,ref));
+            a_reg_alloc(list,NR_R12);
+            list.concat(Taicpu.op_reg_ref(A_LDR,NR_R12,ref));
             current_asmdata.getaddrlabel(l);
             current_procinfo.aktlocaldata.concat(tai_const.Create_rel_sym_offset(aitconst_32bit,l,current_asmdata.RefAsmSymbol('_GLOBAL_OFFSET_TABLE_'),-8));
             cg.a_label(list,l);
-            list.concat(Taicpu.op_reg_reg_reg(A_ADD,current_procinfo.got,NR_PC,current_procinfo.got));
+            if cs_opt_regvar in current_settings.optimizerswitches then
+              begin
+                {
+                  When regvars are used, it is needed to perform GOT calculations using the scratch register R12
+                  and then MOV the result to the GOT register. Otherwise the register allocator will use
+                  register R0 as temp to perform calculations in case if a procedure uses all available registers.
+                  It leads to corruption of R0 which is normally holds a value of the first procedure parameter.
+                }
+                list.concat(Taicpu.op_reg_reg_reg(A_ADD,NR_R12,NR_PC,NR_R12));
+                list.concat(Taicpu.op_reg_reg(A_MOV,current_procinfo.got,NR_R12));
+              end
+            else
+              list.concat(Taicpu.op_reg_reg_reg(A_ADD,current_procinfo.got,NR_PC,NR_R12));
+            a_reg_dealloc(list,NR_R12);
           end;
       end;
 
diff --git a/compiler/arm/cpupi.pas b/compiler/arm/cpupi.pas
index 3d69b85da0..30cd892d11 100644
--- a/compiler/arm/cpupi.pas
+++ b/compiler/arm/cpupi.pas
@@ -265,7 +265,7 @@ unit cpupi;
       begin
         { darwin doesn't use a got }
         if tf_pic_uses_got in target_info.flags then
-          got := NR_PIC_OFFSET_REG;
+          got := cg.getaddressregister(list);
       end;