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llvm-project/llvm/test/CodeGen/X86/2008-03-10-RegAllocInfLoop.ll

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When the register allocator runs out of registers, spill a physical register around the def's and use's of the interval being allocated to make it possible for the interval to target a register and spill it right away and restore a register for uses. This likely generates terrible code but is before than aborting. llvm-svn: 48218
2008-03-11 15:19:34 +08:00
; RUN: llvm-as < %s | llc -mtriple=i386-pc-linux-gnu -relocation-model=pic -disable-fp-elim
Experimental scheduler change to schedule / coalesce the copies added for function livein's. Take 2008-03-10-RegAllocInfLoop.ll, the schedule looks like this after these copies are inserted: entry: 0x12049d0, LLVM BB @0x1201fd0, ID#0: Live Ins: %EAX %EDX %ECX %reg1031<def> = MOVPC32r 0 %reg1032<def> = ADD32ri %reg1031, <es:_GLOBAL_OFFSET_TABLE_>, %EFLAGS<imp-def> %reg1028<def> = MOV32rr %EAX %reg1029<def> = MOV32rr %EDX %reg1030<def> = MOV32rr %ECX %reg1027<def> = MOV8rm %reg0, 1, %reg0, 0, Mem:LD(1,1) [0x1201910 + 0] %reg1025<def> = MOV32rr %reg1029 %reg1026<def> = MOV32rr %reg1030 %reg1024<def> = MOV32rr %reg1028 The copies unnecessarily increase register pressure and it will end up requiring a physical register to be spilled. With -schedule-livein-copies: entry: 0x12049d0, LLVM BB @0x1201fa0, ID#0: Live Ins: %EAX %EDX %ECX %reg1031<def> = MOVPC32r 0 %reg1032<def> = ADD32ri %reg1031, <es:_GLOBAL_OFFSET_TABLE_>, %EFLAGS<imp-def> %reg1024<def> = MOV32rr %EAX %reg1025<def> = MOV32rr %EDX %reg1026<def> = MOV32rr %ECX %reg1027<def> = MOV8rm %reg0, 1, %reg0, 0, Mem:LD(1,1) [0x12018e0 + 0] Much better! llvm-svn: 48307
2008-03-13 06:19:41 +08:00
; RUN: llvm-as < %s | llc -mtriple=i386-pc-linux-gnu -relocation-model=pic -disable-fp-elim -schedule-livein-copies | not grep {Number of register spills}
When the register allocator runs out of registers, spill a physical register around the def's and use's of the interval being allocated to make it possible for the interval to target a register and spill it right away and restore a register for uses. This likely generates terrible code but is before than aborting. llvm-svn: 48218
2008-03-11 15:19:34 +08:00
; PR2134
declare fastcc i8* @w_addchar(i8*, i32*, i32*, i8 signext ) nounwind
define x86_stdcallcc i32 @parse_backslash(i8** inreg %word, i32* inreg %word_length, i32* inreg %max_length) nounwind {
entry:
%tmp6 = load i8* null, align 1 ; <i8> [#uses=1]
br label %bb13
bb13: ; preds = %entry
%tmp26 = call fastcc i8* @w_addchar( i8* null, i32* %word_length, i32* %max_length, i8 signext %tmp6 ) nounwind ; <i8*> [#uses=1]
store i8* %tmp26, i8** %word, align 4
ret i32 0
}