Embarassing, but this fails.

src/alloy/frontend/ppc/test/bin/instr_subfe.dis

@@ -7,3 +7,19 @@ Disassembly of section .text:
 0000000000100000 <test_subfe>:
   100000:	7c 6a 59 10 	subfe   r3,r10,r11
   100004:	4e 80 00 20 	blr
+
+0000000000100008 <test_subfe_2>:
+  100008:	7c 6a 59 10 	subfe   r3,r10,r11
+  10000c:	4e 80 00 20 	blr
+
+0000000000100010 <test_subfe_3>:
+  100010:	7c 6a 59 10 	subfe   r3,r10,r11
+  100014:	4e 80 00 20 	blr
+
+0000000000100018 <test_subfe_4>:
+  100018:	7c 6a 59 10 	subfe   r3,r10,r11
+  10001c:	4e 80 00 20 	blr
+
+0000000000100020 <test_subfe_5>:
+  100020:	7c 6a 59 10 	subfe   r3,r10,r11
+  100024:	4e 80 00 20 	blr

src/alloy/frontend/ppc/test/bin/instr_subfe.map

@@ -1 +1,5 @@
 0000000000000000 t test_subfe
+0000000000000008 t test_subfe_2
+0000000000000010 t test_subfe_3
+0000000000000018 t test_subfe_4
+0000000000000020 t test_subfe_5

src/alloy/frontend/ppc/test/instr_subfe.s

@@ -1,10 +1,44 @@
 test_subfe:
   #_ REGISTER_IN r10 0x00000000000103BF
   #_ REGISTER_IN r11 0x00000000000103C0
-
   subfe r3, r10, r11
-
   blr
   #_ REGISTER_OUT r10 0x00000000000103BF
   #_ REGISTER_OUT r11 0x00000000000103C0
-  #_ REGISTER_OUT r3 0x1
+  #_ REGISTER_OUT r3 0x0
+
+test_subfe_2:
+  #_ REGISTER_IN r10 0
+  #_ REGISTER_IN r11 0
+  subfe r3, r10, r11
+  blr
+  #_ REGISTER_OUT r10 0
+  #_ REGISTER_OUT r11 0
+  #_ REGISTER_OUT r3 0
+
+test_subfe_3:
+  #_ REGISTER_IN r10 1
+  #_ REGISTER_IN r11 0
+  subfe r3, r10, r11
+  blr
+  #_ REGISTER_OUT r10 1
+  #_ REGISTER_OUT r11 0
+  #_ REGISTER_OUT r3 -1
+
+test_subfe_4:
+  #_ REGISTER_IN r10 0
+  #_ REGISTER_IN r11 1
+  subfe r3, r10, r11
+  blr
+  #_ REGISTER_OUT r10 0
+  #_ REGISTER_OUT r11 1
+  #_ REGISTER_OUT r3 0
+
+test_subfe_5:
+  #_ REGISTER_IN r10 0xFFFFFFFFFFFFFFFF
+  #_ REGISTER_IN r11 0xFFFFFFFFFFFFFFFF
+  subfe r3, r10, r11
+  blr
+  #_ REGISTER_OUT r10 0xFFFFFFFFFFFFFFFF
+  #_ REGISTER_OUT r11 0xFFFFFFFFFFFFFFFF
+  #_ REGISTER_OUT r3 0x0