From da54d0e8f7efb83515a85c84b49c9311001f777f Mon Sep 17 00:00:00 2001
From: florian <florian@freepascal.org>
Date: Wed, 20 Nov 2019 22:12:27 +0000
Subject: [PATCH]   + patch by J. Gareth Moreton: new method
 TAOptObj.CanDoJumpOpts and arm specific implementation

git-svn-id: trunk@43519 -
---
 compiler/aoptobj.pas     | 44 +++++++++++++++++++++++-----------------
 compiler/arm/aoptcpu.pas | 13 ++++++++++++
 2 files changed, 38 insertions(+), 19 deletions(-)

diff --git a/compiler/aoptobj.pas b/compiler/aoptobj.pas
index aa4a870ffc..45241a9734 100644
--- a/compiler/aoptobj.pas
+++ b/compiler/aoptobj.pas
@@ -401,6 +401,9 @@ Unit AoptObj;
         function OptimizeConditionalJump(CJLabel: TAsmLabel; var p: tai; hp1: tai; var stoploop: Boolean): Boolean;
 {$endif JVM}
 
+        { Function to determine if the jump optimisations can be performed }
+        function CanDoJumpOpts: Boolean; virtual;
+
         { Jump/label optimisation entry method }
         function DoJumpOptimizations(var p: tai; var stoploop: Boolean): Boolean;
 
@@ -2105,6 +2108,13 @@ Unit AoptObj;
     end;
 
 
+    function TAOptObj.CanDoJumpOpts: Boolean;
+      begin
+        { Always allow by default }
+        Result := True;
+      end;
+
+
     function TAOptObj.DoJumpOptimizations(var p: tai; var stoploop: Boolean): Boolean;
       var
         hp1, hp2: tai;
@@ -2356,8 +2366,10 @@ Unit AoptObj;
     procedure TAOptObj.PeepHoleOptPass1;
       var
         p,hp1,hp2,hp3 : tai;
-        stoploop, FirstInstruction: boolean;
+        stoploop, FirstInstruction, JumpOptsAvailable: boolean;
       begin
+        JumpOptsAvailable := CanDoJumpOpts();
+
         StartPoint := BlockStart;
 
         repeat
@@ -2379,25 +2391,19 @@ Unit AoptObj;
                 InsertLLItem(tai(p.Previous),p,tai_comment.create(strpnew(GetAllocationString(UsedRegs))));
 {$endif DEBUG_OPTALLOC}
 
-              { Handle Jmp Optimizations first }
-{$if defined(ARM)}
-              { Cannot perform these jump optimisations if the ARM architecture has 16-bit thumb codes }
-              if not (
-                (current_settings.instructionset = is_thumb) and not(CPUARM_HAS_THUMB2 in cpu_capabilities[current_settings.cputype])
-              ) then
-{$endif defined(ARM)}
-                if DoJumpOptimizations(p, stoploop) then
-                  begin
-                    UpdateUsedRegs(p);
-                    if FirstInstruction then
-                      { Update StartPoint, since the old p was removed;
-                        don't set FirstInstruction to False though, as
-                        the new p might get removed too. }
-                      StartPoint := p;
+              { Handle jump optimizations first }
+              if JumpOptsAvailable and DoJumpOptimizations(p, stoploop) then
+                begin
+                  UpdateUsedRegs(p);
+                  if FirstInstruction then
+                    { Update StartPoint, since the old p was removed;
+                      don't set FirstInstruction to False though, as
+                      the new p might get removed too. }
+                    StartPoint := p;
 
-                    if (p.typ = ait_instruction) and IsJumpToLabel(taicpu(p)) then
-                      Continue;
-                  end;
+                  if (p.typ = ait_instruction) and IsJumpToLabel(taicpu(p)) then
+                    Continue;
+                end;
 
               if PeepHoleOptPass1Cpu(p) then
                 begin
diff --git a/compiler/arm/aoptcpu.pas b/compiler/arm/aoptcpu.pas
index 487fe349ab..107cfdb69d 100644
--- a/compiler/arm/aoptcpu.pas
+++ b/compiler/arm/aoptcpu.pas
@@ -34,6 +34,9 @@ uses cgbase, cgutils, cpubase, aasmtai, aasmcpu,aopt, aoptobj;
 
 Type
   TCpuAsmOptimizer = class(TAsmOptimizer)
+    { Can't be done in some cases due to the limited range of jumps }
+    function CanDoJumpOpts: Boolean; override;
+
     { uses the same constructor as TAopObj }
     function PeepHoleOptPass1Cpu(var p: tai): boolean; override;
     procedure PeepHoleOptPass2;override;
@@ -379,6 +382,16 @@ Implementation
     end;
 {$endif DEBUG_AOPTCPU}
 
+
+  function TCpuAsmOptimizer.CanDoJumpOpts: Boolean;
+    begin
+      { Cannot perform these jump optimisations if the ARM architecture has 16-bit thumb codes }
+      Result := not (
+        (current_settings.instructionset = is_thumb) and not (CPUARM_HAS_THUMB2 in cpu_capabilities[current_settings.cputype])
+      );
+    end;
+
+
   function TCpuAsmOptimizer.RemoveSuperfluousMove(const p: tai; movp: tai; const optimizer: string):boolean;
     var
       alloc,