Emit sub r, #c instead of transforming it to add r, #-c if c fits in 8-bit. This is a bit of pre-mature optimization. 8-bit variant makes it likely it will be narrowed to a 16-bit instruction.

llvm-svn: 78030

1 files changed, 19 insertions, 1 deletions

diff --git a/llvm/test/CodeGen/Thumb2/thumb2-sub.ll b/llvm/test/CodeGen/Thumb2/thumb2-sub.ll
index a7c9676b978..74accdcb8ea 100644
--- a/llvm/test/CodeGen/Thumb2/thumb2-sub.ll
+++ b/llvm/test/CodeGen/Thumb2/thumb2-sub.ll
@@ -1,31 +1,49 @@
-; RUN: llvm-as < %s | llc -march=thumb -mattr=+thumb2 | grep {sub\\.w\\W*r\[0-9\],\\W*r\[0-9\],\\W*#\[0-9\]*} | grep {#171\\|#1179666\\|#872428544\\|#1448498774\\|#510} | count 5
+; RUN: llvm-as < %s | llc -march=thumb -mattr=+thumb2 | FileCheck %s
 
 ; 171 = 0x000000ab
 define i32 @f1(i32 %a) {
+; CHECK: f1:
+; CHECK: sub.w r0, r0, #171
     %tmp = sub i32 %a, 171
     ret i32 %tmp
 }
 
 ; 1179666 = 0x00120012
 define i32 @f2(i32 %a) {
+; CHECK: f2:
+; CHECK: sub.w r0, r0, #1179666
     %tmp = sub i32 %a, 1179666
     ret i32 %tmp
 }
 
 ; 872428544 = 0x34003400
 define i32 @f3(i32 %a) {
+; CHECK: f3:
+; CHECK: sub.w r0, r0, #872428544
     %tmp = sub i32 %a, 872428544
     ret i32 %tmp
 }
 
 ; 1448498774 = 0x56565656
 define i32 @f4(i32 %a) {
+; CHECK: f4:
+; CHECK: sub.w r0, r0, #1448498774
     %tmp = sub i32 %a, 1448498774
     ret i32 %tmp
 }
 
 ; 510 = 0x000001fe
 define i32 @f5(i32 %a) {
+; CHECK: f5:
+; CHECK: sub.w r0, r0, #510
     %tmp = sub i32 %a, 510
     ret i32 %tmp
 }
+
+; Don't change this to an add.
+define i32 @f6(i32 %a) {
+; CHECK: f6:
+; CHECK: sub.w r0, r0, #1
+    %tmp = sub i32 %a, 1
+    ret i32 %tmp
+}