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; RUN: opt -S < %s -passes='loop-unroll,load-store-vectorizer' -unroll-count=128 --capture-tracking-max-uses-to-explore=1024 | FileCheck %s
; Without using batching alias analysis, this test takes 6 seconds to compile. With, less than a second.
; This is because the mechanism that proves NoAlias in this case is very expensive (CaptureTracking.cpp),
; and caching the result leads to 2 calls to that mechanism instead of ~300,000 (run with -stats to see the difference)
; This test only demonstrates the compile time issue if capture-tracking-max-uses-to-explore is set to at least 1024,
; because with the default value of 100, the CaptureTracking analysis is not run, NoAlias is not proven, and the vectorizer gives up early.
@global_mem = external global i8, align 4
define void @compile-time-test() {
; CHECK-LABEL: define void @compile-time-test() {
; CHECK-COUNT-128: load <4 x i8>
entry:
; Create base pointer to a global variable with the inefficient pattern that Alias Analysis cannot easily traverse through.
%global_base_loads = getelementptr i8, ptr inttoptr (i32 ptrtoint (ptr @global_mem to i32) to ptr), i64 0
; Create another pointer for the stores.
%local_base_stores = alloca <512 x i8>, align 4
; 512 interwoven loads and stores in a loop that gets unrolled
br label %loop
loop:
%i = phi i64 [ 0, %entry ], [ %i_next, %loop ]
%ptr_0 = getelementptr i8, ptr %global_base_loads, i64 %i
%load_0 = load i8, ptr %ptr_0, align 4
%ptr2_0 = getelementptr i8, ptr %local_base_stores, i64 %i
store i8 %load_0, ptr %ptr2_0, align 4
%i_1 = add i64 %i, 1
%ptr_1 = getelementptr i8, ptr %global_base_loads, i64 %i_1
%load_1 = load i8, ptr %ptr_1, align 1
%ptr2_1 = getelementptr i8, ptr %local_base_stores, i64 %i_1
store i8 %load_1, ptr %ptr2_1, align 1
%i_2 = add i64 %i, 2
%ptr_2 = getelementptr i8, ptr %global_base_loads, i64 %i_2
%load_2 = load i8, ptr %ptr_2, align 2
%ptr2_2 = getelementptr i8, ptr %local_base_stores, i64 %i_2
store i8 %load_2, ptr %ptr2_2, align 2
%i_3 = add i64 %i, 3
%ptr_3 = getelementptr i8, ptr %global_base_loads, i64 %i_3
%load_3 = load i8, ptr %ptr_3, align 1
%ptr2_3 = getelementptr i8, ptr %local_base_stores, i64 %i_3
store i8 %load_3, ptr %ptr2_3, align 1
%i_next = add i64 %i, 4
%cmp = icmp ult i64 %i_next, 512
br i1 %cmp, label %loop, label %done
done:
ret void
}
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