+ ARM internal linker: very initial support for Thumb mode, helloworld-class programs compiled with "-Cparmv6m -CIthumb" can now run.

git-svn-id: trunk@28697 -

compiler/arm/cpuelf.pas

@@ -561,6 +561,7 @@ implementation
     rotation:longint;
     residual,g_n:longword;
     curloc: aword;
+    bit_S,bit_I1,bit_I2: aint;
   begin
     data:=objsec.data;
     for i:=0 to objsec.ObjRelocations.Count-1 do
@@ -660,7 +661,16 @@ implementation
                   2) when target is unresolved weak symbol, CALL must be changed to NOP,
                   while JUMP24 behavior is unspecified. }
                 tmp:=sarlongint((address and $00FFFFFF) shl 8,6);
-                tmp:=tmp+relocval-curloc;
+                tmp:=tmp+relocval;
+                if odd(tmp) then    { dest is Thumb? }
+                  begin
+                    if (reltyp=R_ARM_CALL) then
+                      { change BL to BLX, dest bit 1 goes to instruction bit 24 }
+                      address:=(address and $FE000000) or (((tmp-curloc) and 2) shl 23) or $10000000
+                    else
+                      InternalError(2014092001);
+                  end;
+                tmp:=tmp-curloc;
                 // TODO: check overflow
                 address:=(address and $FF000000) or ((tmp and $3FFFFFE) shr 2);
               end;
@@ -829,6 +839,38 @@ implementation
                   address:=address or (1 shl 23);
               end;
 
+            R_ARM_THM_CALL:
+              begin
+                if (not ElfTarget.relocs_use_addend) then
+                  begin
+                    address:=((address and $ffff) shl 16) or word(address shr 16);
+                    bit_S:=(address shr 26) and 1;
+                    bit_I1:=(bit_S xor ((address shr 13) and 1)) xor 1;
+                    bit_I2:=(bit_S xor ((address shr 11) and 1)) xor 1;
+                    tmp:=((-bit_S) shl 24) or (bit_I1 shl 23) or (bit_I2 shl 22) or (((address shr 16) and $3ff) shl 12) or ((address and $7ff) shl 1);
+                  end
+                else  { TODO: must read the instruction anyway }
+                  tmp:=address;
+                tmp:=tmp+relocval;       { dest address }
+                if odd(tmp) then         { if it's Thumb code, change possible BLX to BL }
+                  address:=address or $1800;
+                tmp:=tmp-curloc;         { now take PC-relative }
+                { TODO: overflow check, different limit for Thumb and Thumb-2 }
+
+                { now encode this mess back }
+                if (address and $5000)=$4000 then
+                  tmp:=(tmp+2) and (not 3);
+
+                bit_S:=(tmp shr 31) and 1;
+                address:=(address and $F800D000) or
+                  (bit_S shl 26) or
+                  (((tmp shr 12) and $3ff) shl 16) or
+                  ((tmp shr 1) and $7FF) or
+                  ((((tmp shr 23) and 1) xor 1 xor bit_S) shl 13) or
+                  ((((tmp shr 22) and 1) xor 1 xor bit_S) shl 11);
+                address:=((address and $ffff) shl 16) or word(address shr 16);
+              end;
+
             R_ARM_TLS_IE32:
               begin
                 relocval:=relocval-tlsseg.mempos+align_aword(TCB_SIZE,tlsseg.align);