llvm-6502/test/CodeGen/Thumb/ldm-merge-call.ll
Moritz Roth d84561bf69 ARM: Fix and re-enable load/store optimizer for Thumb1.
In a previous iteration of the pass, we would try to compensate for
writeback by updating later instructions and/or inserting a SUBS to
reset the base register if necessary.
Since such a SUBS sets the condition flags it's not generally safe to do
this. For now, only merge LDR/STRs if there is no writeback to the base
register (LDM that loads into the base register) or the base register is
killed by one of the merged instructions. These cases are clear wins
both in terms of instruction count and performance.

Also add three new test cases, and update the existing ones accordingly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215729 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-15 17:00:30 +00:00

25 lines
1.2 KiB
LLVM

; RUN: llc -mtriple=thumbv6m-eabi -verify-machineinstrs %s -o - | FileCheck %s
target datalayout = "e-m:e-p:32:32-i1:8:32-i8:8:32-i16:16:32-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "thumbv6m--linux-gnueabi"
; Function Attrs: nounwind optsize
define void @foo(i32* nocapture readonly %A) #0 {
entry:
; CHECK-LABEL: foo:
; CHECK: ldm r[[BASE:[0-9]]]!,
; CHECK-NEXT: mov r[[BASE]],
%0 = load i32* %A, align 4
%arrayidx1 = getelementptr inbounds i32* %A, i32 1
%1 = load i32* %arrayidx1, align 4
%call = tail call i32 @bar(i32 %0, i32 %1, i32 %0, i32 %1) #2
%call2 = tail call i32 @bar(i32 %0, i32 %1, i32 %0, i32 %1) #2
ret void
}
; Function Attrs: optsize
declare i32 @bar(i32, i32, i32, i32) #1
attributes #0 = { nounwind optsize "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { optsize "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #2 = { nounwind optsize }