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llvm-mirror/test/CodeGen/Thumb/thumb-ldm.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

43 lines
1.6 KiB
LLVM

; RUN: llc < %s -mtriple=thumbv6m-eabi -verify-machineinstrs -o - | FileCheck %s
@X = external global [0 x i32] ; <[0 x i32]*> [#uses=5]
define i32 @t1() {
; CHECK-LABEL: t1:
; CHECK: push {r7, lr}
; CHECK: ldm
; CHECK: pop {r7, pc}
%tmp = load i32* getelementptr ([0 x i32]* @X, i32 0, i32 0) ; <i32> [#uses=1]
%tmp3 = load i32* getelementptr ([0 x i32]* @X, i32 0, i32 1) ; <i32> [#uses=1]
%tmp4 = call i32 @f1( i32 %tmp, i32 %tmp3 ) ; <i32> [#uses=1]
ret i32 %tmp4
}
define i32 @t2() {
; CHECK-LABEL: t2:
; CHECK: push {r7, lr}
; CHECK: ldm
; CHECK: pop {r7, pc}
%tmp = load i32* getelementptr ([0 x i32]* @X, i32 0, i32 2) ; <i32> [#uses=1]
%tmp3 = load i32* getelementptr ([0 x i32]* @X, i32 0, i32 3) ; <i32> [#uses=1]
%tmp5 = load i32* getelementptr ([0 x i32]* @X, i32 0, i32 4) ; <i32> [#uses=1]
%tmp6 = call i32 @f2( i32 %tmp, i32 %tmp3, i32 %tmp5 ) ; <i32> [#uses=1]
ret i32 %tmp6
}
define i32 @t3() {
; CHECK-LABEL: t3:
; CHECK: push {r7, lr}
; CHECK: ldm
; CHECK: pop {r7, pc}
%tmp = load i32* getelementptr ([0 x i32]* @X, i32 0, i32 1) ; <i32> [#uses=1]
%tmp3 = load i32* getelementptr ([0 x i32]* @X, i32 0, i32 2) ; <i32> [#uses=1]
%tmp5 = load i32* getelementptr ([0 x i32]* @X, i32 0, i32 3) ; <i32> [#uses=1]
%tmp6 = call i32 @f2( i32 %tmp, i32 %tmp3, i32 %tmp5 ) ; <i32> [#uses=1]
ret i32 %tmp6
}
declare i32 @f1(i32, i32)
declare i32 @f2(i32, i32, i32)