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llvm-mirror/test/CodeGen/ARM/t2-shrink-ldrpost.ll
James Molloy 7a93cbe27f [ARM] Shrink post-indexed LDR and STR to LDM/STM
A Thumb-2 post-indexed LDR instruction such as:

  ldr.w r0, [r1], #4

Can be rewritten as:

  ldm.n r1!, {r0}

LDMs can be more expensive than LDRs on some cores, so this has been enabled only in minsize mode.

llvm-svn: 272002
2016-06-07 12:13:34 +00:00

53 lines
1.9 KiB
LLVM

; RUN: llc < %s | FileCheck %s
target datalayout = "e-m:e-p:32:32-i1:8:32-i8:8:32-i16:16:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"
target triple = "thumbv7m--linux-gnu"
; CHECK-LABEL: f:
; CHECK: ldm r{{[0-9]}}!, {r[[x:[0-9]]]}
; CHECK: add.w r[[x]], r[[x]], #3
; CHECK: stm r{{[0-9]}}!, {r[[x]]}
define void @f(i32 %n, i32* nocapture %a, i32* nocapture readonly %b) optsize minsize {
%1 = icmp sgt i32 %n, 0
br i1 %1, label %.lr.ph, label %._crit_edge
.lr.ph: ; preds = %.lr.ph, %0
%i.04 = phi i32 [ %6, %.lr.ph ], [ 0, %0 ]
%.03 = phi i32* [ %2, %.lr.ph ], [ %b, %0 ]
%.012 = phi i32* [ %5, %.lr.ph ], [ %a, %0 ]
%2 = getelementptr inbounds i32, i32* %.03, i32 1
%3 = load i32, i32* %.03, align 4
%4 = add nsw i32 %3, 3
%5 = getelementptr inbounds i32, i32* %.012, i32 1
store i32 %4, i32* %.012, align 4
%6 = add nsw i32 %i.04, 1
%exitcond = icmp eq i32 %6, %n
br i1 %exitcond, label %._crit_edge, label %.lr.ph
._crit_edge: ; preds = %.lr.ph, %0
ret void
}
; CHECK-LABEL: f_nominsize:
; CHECK-NOT: ldm
define void @f_nominsize(i32 %n, i32* nocapture %a, i32* nocapture readonly %b) optsize {
%1 = icmp sgt i32 %n, 0
br i1 %1, label %.lr.ph, label %._crit_edge
.lr.ph: ; preds = %.lr.ph, %0
%i.04 = phi i32 [ %6, %.lr.ph ], [ 0, %0 ]
%.03 = phi i32* [ %2, %.lr.ph ], [ %b, %0 ]
%.012 = phi i32* [ %5, %.lr.ph ], [ %a, %0 ]
%2 = getelementptr inbounds i32, i32* %.03, i32 1
%3 = load i32, i32* %.03, align 4
%4 = add nsw i32 %3, 3
%5 = getelementptr inbounds i32, i32* %.012, i32 1
store i32 %4, i32* %.012, align 4
%6 = add nsw i32 %i.04, 1
%exitcond = icmp eq i32 %6, %n
br i1 %exitcond, label %._crit_edge, label %.lr.ph
._crit_edge: ; preds = %.lr.ph, %0
ret void
}