hipe_x86: Fix encoding of test instr w/ neg imm

Also, use byte form for immediates up to 255, since there's no sign
extension in byte form.

HiPE seems to never generate negative test immediates currently, but we
should at least not output incorrect encodings.

1 files changed, 22 insertions, 15 deletions

diff --git a/lib/hipe/x86/hipe_x86_assemble.erl b/lib/hipe/x86/hipe_x86_assemble.erl
index 4986933f50..e692ff0ebb 100644
--- a/lib/hipe/x86/hipe_x86_assemble.erl
+++ b/lib/hipe/x86/hipe_x86_assemble.erl
@@ -888,22 +888,29 @@ resolve_alu_args(Src, Dst, Context) ->
 %%% test
 resolve_test_args(Src, Dst, Context) ->
   case Src of
-    #x86_imm{} ->
-      Imm = translate_imm(Src, Context, false),
-      case Imm of
-	{imm8,_} ->
-	  case Dst of
-	    #x86_temp{reg=0} -> {al, Imm};
-	    #x86_temp{} -> resolve_test_imm8_reg(Imm, Dst);
-	    #x86_mem{} -> {mem_to_rm8(Dst), Imm}
-	  end;
-	{imm32,_} ->
-	  {case Dst of
-	     #x86_temp{reg=0} -> eax;
-	     #x86_temp{} -> temp_to_rm32(Dst);
-	     #x86_mem{} -> mem_to_rm32(Dst)
-	   end, Imm}
+    %% Since we're using an 8-bit instruction, the immediate is not sign
+    %% extended. Thus, we can use immediates up to 255.
+    #x86_imm{value=ImmVal}
+      when is_integer(ImmVal), ImmVal >= 0, ImmVal =< 255 ->
+      Imm = {imm8, ImmVal},
+      case Dst of
+	#x86_temp{reg=0} -> {al, Imm};
+	#x86_temp{} -> resolve_test_imm8_reg(Imm, Dst);
+	#x86_mem{} -> {mem_to_rm8(Dst), Imm}
       end;
+    #x86_imm{value=ImmVal} when is_integer(ImmVal), ImmVal >= 0 ->
+      {case Dst of
+	 #x86_temp{reg=0} -> eax;
+	 #x86_temp{} -> temp_to_rm32(Dst);
+	 #x86_mem{} -> mem_to_rm32(Dst)
+       end, {imm32, ImmVal}};
+    #x86_imm{} -> % Negative ImmVal; use word-sized instr, imm32
+      {_, ImmVal} = translate_imm(Src, Context, false),
+      {case Dst of
+	 #x86_temp{reg=0} -> ?EAX;
+	 #x86_temp{} -> temp_to_rmArch(Dst);
+	 #x86_mem{} -> mem_to_rmArch(Dst)
+       end, {imm32, ImmVal}};
     #x86_temp{} ->
       NewDst =
 	case Dst of