mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2024-10-24 05:23:45 +02:00
c168f14a53
Summary: Before this change, we didn't use to collect forward dependences since none of the current clients (LV, LDist) required them. The motivation to also collect forward dependences is a new pass LoopLoadElimination (LLE) which discovers store-to-load forwarding opportunities across the loop's backedge. The pass uses both lexically forward or backward loop-carried dependences to detect these opportunities. The new pass also analyzes loop-independent (forward) dependences since they can conflict with the loop-carried dependences in terms of how the data flows through memory. The newly added test only covers loop-carried forward dependences because loop-independent ones are currently categorized as NoDep. The next patch will fix this. The two patches were tested together for compile-time regression. None found in LNT/SPEC. Note that with this change LAA provides all dependences rather than just "interesting" ones. A subsequent NFC patch will remove the now trivial isInterestingDependence and rename the APIs. Reviewers: hfinkel Subscribers: jmolloy, rengolin, llvm-commits Differential Revision: http://reviews.llvm.org/D13254 llvm-svn: 251972
45 lines
1.3 KiB
LLVM
45 lines
1.3 KiB
LLVM
; RUN: opt -loop-accesses -analyze < %s | FileCheck %s
|
|
|
|
; for (unsigned i = 0; i < 100; i++) {
|
|
; A[i+8] = B[i] + 2;
|
|
; C[i] = A[i] * 2;
|
|
; }
|
|
|
|
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
|
|
|
|
define void @f(i32* %A, i32* %B, i32* %C, i64 %N) {
|
|
|
|
; CHECK: Interesting Dependences:
|
|
; CHECK-NEXT: Forward:
|
|
; CHECK-NEXT: store i32 %a_p1, i32* %Aidx_ahead, align 4 ->
|
|
; CHECK-NEXT: %a = load i32, i32* %Aidx, align 4
|
|
|
|
entry:
|
|
br label %for.body
|
|
|
|
for.body: ; preds = %for.body, %entry
|
|
%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
|
|
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
|
|
|
|
%idx = add nuw nsw i64 %indvars.iv, 8
|
|
|
|
%Aidx_ahead = getelementptr inbounds i32, i32* %A, i64 %idx
|
|
%Bidx = getelementptr inbounds i32, i32* %B, i64 %indvars.iv
|
|
%Cidx = getelementptr inbounds i32, i32* %C, i64 %indvars.iv
|
|
%Aidx = getelementptr inbounds i32, i32* %A, i64 %indvars.iv
|
|
|
|
%b = load i32, i32* %Bidx, align 4
|
|
%a_p1 = add i32 %b, 2
|
|
store i32 %a_p1, i32* %Aidx_ahead, align 4
|
|
|
|
%a = load i32, i32* %Aidx, align 4
|
|
%c = mul i32 %a, 2
|
|
store i32 %c, i32* %Cidx, 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
|
|
}
|