| ; 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 |
| } |
| |