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llvm-mirror/test/CodeGen/Thumb/ldm-stm-base-materialization.ll
Moritz Roth 434b09b95f Thumb1 load/store optimizer: Improve code to materialize new base register.
There are two add-immediate instructions in Thumb1: tADDi8 and tADDi3. Only
the latter supports using different source and destination registers, so
whenever we materialize a new base register (at a certain offset) we'd do
so by moving the base register value to the new register and then adding in
place. This patch changes the code to use a single tADDi3 if the offset is
small enough to fit in 3 bits.

Differential Revision: http://reviews.llvm.org/D5006

llvm-svn: 216193
2014-08-21 17:11:03 +00:00

30 lines
1016 B
LLVM

; RUN: llc < %s -mtriple=thumbv6m-eabi -verify-machineinstrs -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-none--eabi"
@a = external global i32*
@b = external global i32*
; Function Attrs: nounwind
define void @foo() #0 {
entry:
; CHECK-LABEL: foo:
; CHECK: ldr r[[SB:[0-9]]], .LCPI
; CHECK: ldr r[[LB:[0-9]]], .LCPI
; CHECK: adds r[[NLB:[0-9]]], r[[LB]], #4
; CHECK-NEXT: ldm r[[NLB]],
; CHECK: adds r[[NSB:[0-9]]], r[[SB]], #4
; CHECK-NEXT: stm r[[NSB]]
%0 = load i32** @a, align 4
%arrayidx = getelementptr inbounds i32* %0, i32 1
%1 = bitcast i32* %arrayidx to i8*
%2 = load i32** @b, align 4
%arrayidx1 = getelementptr inbounds i32* %2, i32 1
%3 = bitcast i32* %arrayidx1 to i8*
tail call void @llvm.memcpy.p0i8.p0i8.i32(i8* %1, i8* %3, i32 24, i32 4, i1 false)
ret void
}
; Function Attrs: nounwind
declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture readonly, i32, i32, i1) #1