llvm-6502/test/CodeGen/X86/twoaddr-coalesce.ll
Evan Cheng 870b80722f Minor optimization:
Look for situations like this:                                                                                                                                                              
%reg1024<def> = MOV r1                                                                                                                                                                      
%reg1025<def> = MOV r0                                                                                                                                                                      
%reg1026<def> = ADD %reg1024, %reg1025                                                                                                                                                      
r0            = MOV %reg1026                                                                                                                                                                
Commute the ADD to hopefully eliminate an otherwise unavoidable copy.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65752 91177308-0d34-0410-b5e6-96231b3b80d8
2009-03-01 02:03:43 +00:00

26 lines
910 B
LLVM

; RUN: llvm-as < %s | llc -march=x86 -stats |& \
; RUN: grep {twoaddrinstr} | grep {Number of instructions aggressively commuted}
; rdar://6523745
@"\01LC" = internal constant [4 x i8] c"%d\0A\00" ; <[4 x i8]*> [#uses=1]
define i32 @main() nounwind {
bb1.thread:
br label %bb1
bb1: ; preds = %bb1, %bb1.thread
%i.0.reg2mem.0 = phi i32 [ 0, %bb1.thread ], [ %indvar.next, %bb1 ] ; <i32> [#uses=2]
%0 = trunc i32 %i.0.reg2mem.0 to i8 ; <i8> [#uses=1]
%1 = sdiv i8 %0, 2 ; <i8> [#uses=1]
%2 = sext i8 %1 to i32 ; <i32> [#uses=1]
%3 = tail call i32 (i8*, ...)* @printf(i8* getelementptr ([4 x i8]* @"\01LC", i32 0, i32 0), i32 %2) nounwind ; <i32> [#uses=0]
%indvar.next = add i32 %i.0.reg2mem.0, 1 ; <i32> [#uses=2]
%exitcond = icmp eq i32 %indvar.next, 258 ; <i1> [#uses=1]
br i1 %exitcond, label %bb2, label %bb1
bb2: ; preds = %bb1
ret i32 0
}
declare i32 @printf(i8*, ...) nounwind