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; RUN: opt -passes=loop-load-elim -S < %s | FileCheck %s
; Simple st->ld forwarding derived from a lexical backward dep.
;
; for (unsigned i = 0; i < 100; i++)
; A[i+1] = A[i] + B[i];
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
define void @f(ptr noalias nocapture %A, ptr noalias nocapture readonly %B, i64 %N) {
entry:
; CHECK: %load_initial = load i32, ptr %A
br label %for.body
for.body: ; preds = %for.body, %entry
; CHECK: %store_forwarded = phi i32 [ %load_initial, %entry ], [ %add, %for.body ]
%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
%arrayidx = getelementptr inbounds i32, ptr %A, i64 %indvars.iv
%load = load i32, ptr %arrayidx, align 4
%arrayidx2 = getelementptr inbounds i32, ptr %B, i64 %indvars.iv
%load_1 = load i32, ptr %arrayidx2, align 4
; CHECK: %add = add i32 %load_1, %store_forwarded
%add = add i32 %load_1, %load
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%arrayidx_next = getelementptr inbounds i32, ptr %A, i64 %indvars.iv.next
store i32 %add, ptr %arrayidx_next, align 4
%exitcond = icmp eq i64 %indvars.iv.next, %N
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
ret void
}
; Same but loop is descending.
;
; for (unsigned i = N; i > 0; i--)
; A[i-1] = A[i] + B[i];
define void @g(ptr noalias nocapture %A, ptr noalias nocapture readonly %B, i64 %N) {
entry:
; CHECK: %0 = shl i64 %N, 2
; CHECK: %scevgep = getelementptr i8, ptr %A, i64 %0
; CHECK: %load_initial = load i32, ptr %scevgep, align 4
br label %for.body
for.body: ; preds = %for.body, %entry
; CHECK: %store_forwarded = phi i32 [ %load_initial, %entry ], [ %add, %for.body ]
%i.09 = phi i64 [ %sub, %for.body ], [ %N, %entry ]
%arrayidx = getelementptr inbounds i32, ptr %A, i64 %i.09
%load = load i32, ptr %arrayidx, align 4
%arrayidx1 = getelementptr inbounds i32, ptr %B, i64 %i.09
%load_1 = load i32, ptr %arrayidx1, align 4
; CHECK: %add = add i32 %load_1, %store_forwarded
%add = add i32 %load_1, %load
%sub = add i64 %i.09, -1
%arrayidx2 = getelementptr inbounds i32, ptr %A, i64 %sub
store i32 %add, ptr %arrayidx2, align 4
%cmp.not = icmp eq i64 %sub, 0
br i1 %cmp.not, label %for.end, label %for.body
for.end: ; preds = %for.body
ret void
}
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