1; RUN: opt -passes='print<access-info>' %s -disable-output 2>&1 | FileCheck %s 2 3; This test verifies run-time boundary check of memory accesses. 4; The original loop: 5; void fastCopy(const char* src, char* op) { 6; int len = 32; 7; while (len > 0) { 8; *(reinterpret_cast<long long*>(op)) = *(reinterpret_cast<const long long*>(src)); 9; src += 8; 10; op += 8; 11; len -= 8; 12; } 13; } 14; Boundaries calculations before this patch: 15; (Low: %src High: (24 + %src)) 16; and the actual distance between two pointers was 31, (%op - %src = 31) 17; IsConflict = (24 > 31) = false -> execution is directed to the vectorized loop. 18; The loop was vectorized to 4, 32 byte memory access ( <4 x i64> ), 19; store a value at *%op touched memory under *%src. 20 21;CHECK: function 'fastCopy': 22;CHECK: (Low: %op High: (32 + %op)) 23;CHECK: (Low: %src High: (32 + %src)) 24 25define void @fastCopy(ptr nocapture readonly %src, ptr nocapture %op) { 26entry: 27 br label %while.body.preheader 28 29while.body.preheader: ; preds = %entry 30 br label %while.body 31 32while.body: ; preds = %while.body.preheader, %while.body 33 %len.addr.07 = phi i32 [ %sub, %while.body ], [ 32, %while.body.preheader ] 34 %op.addr.06 = phi ptr [ %add.ptr1, %while.body ], [ %op, %while.body.preheader ] 35 %src.addr.05 = phi ptr [ %add.ptr, %while.body ], [ %src, %while.body.preheader ] 36 %0 = load i64, ptr %src.addr.05, align 8 37 store i64 %0, ptr %op.addr.06, align 8 38 %add.ptr = getelementptr inbounds i8, ptr %src.addr.05, i64 8 39 %add.ptr1 = getelementptr inbounds i8, ptr %op.addr.06, i64 8 40 %sub = add nsw i32 %len.addr.07, -8 41 %cmp = icmp sgt i32 %len.addr.07, 8 42 br i1 %cmp, label %while.body, label %while.end.loopexit 43 44while.end.loopexit: ; preds = %while.body 45 br label %while.end 46 47while.end: ; preds = %while.end.loopexit, %entry 48 ret void 49} 50