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llvm-mirror/test/CodeGen/ARM/lsr-icmp-imm.ll
James Molloy 36bdf2dfda [Thumb] Select (CMPZ X, -C) -> (CMPZ (ADDS X, C), 0)
The CMPZ #0 disappears during peepholing, leaving just a tADDi3, tADDi8 or t2ADDri. This avoids having to materialize the expensive negative constant in Thumb-1, and allows a shrinking from a 32-bit CMN to a 16-bit ADDS in Thumb-2.

llvm-svn: 281040
2016-09-09 12:52:24 +00:00

35 lines
1.5 KiB
LLVM

; RUN: llc -mtriple=thumbv7-apple-ios -disable-block-placement < %s | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-T
; RUN: llc -mtriple=armv7-apple-ios -disable-block-placement < %s | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-A
; LSR should compare against the post-incremented induction variable.
; In this case, the immediate value is -2 which requires a cmn instruction.
;
; CHECK-LABEL: f:
; CHECK: %for.body
; CHECK: sub{{.*}}[[IV:r[0-9]+]], #2
; CHECK-T: adds{{.*}}[[IV]], #2
; CHECK-A: cmn{{.*}}[[IV]], #2
; CHECK: bne
define i32 @f(i32* nocapture %a, i32 %i) nounwind readonly ssp {
entry:
%cmp3 = icmp eq i32 %i, -2
br i1 %cmp3, label %for.end, label %for.body
for.body: ; preds = %entry, %for.body
%bi.06 = phi i32 [ %i.addr.0.bi.0, %for.body ], [ 0, %entry ]
%i.addr.05 = phi i32 [ %sub, %for.body ], [ %i, %entry ]
%b.04 = phi i32 [ %.b.0, %for.body ], [ 0, %entry ]
%arrayidx = getelementptr inbounds i32, i32* %a, i32 %i.addr.05
%0 = load i32, i32* %arrayidx, align 4
%cmp1 = icmp sgt i32 %0, %b.04
%.b.0 = select i1 %cmp1, i32 %0, i32 %b.04
%i.addr.0.bi.0 = select i1 %cmp1, i32 %i.addr.05, i32 %bi.06
%sub = add nsw i32 %i.addr.05, -2
%cmp = icmp eq i32 %i.addr.05, 0
br i1 %cmp, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
%bi.0.lcssa = phi i32 [ 0, %entry ], [ %i.addr.0.bi.0, %for.body ]
ret i32 %bi.0.lcssa
}