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[AMDGPU][LoopUnroll] Increase BB size to analyze for complete unroll.

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The `UnrollMaxBlockToAnalyze` parameter is used at the stage when we have no
information about a loop body BB cost. In some cases, e.g. for simple loop
```
for(int i=0; i<32; ++i){
  D = Arr2[i*8 + C1];
  Arr1[i*64 + C2] += C3 * D;
  Arr1[i*64 + C2 + 2048] += C4 * D;
}

```
current default parameter value is not enough to run deeper cost analyze so the
loop is not completely unrolled.

Reviewed By: rampitec

Differential Revision: https://reviews.llvm.org/D86248
This commit is contained in:
dfukalov 2020-08-20 00:14:14 +03:00
parent 014e02db94
commit 2c00c94c18
2 changed files with 26 additions and 19 deletions
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2
lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp
View File

@ -82,7 +82,7 @@ static cl::opt<bool> UseLegacyDA(
static cl::opt<unsigned> UnrollMaxBlockToAnalyze(
"amdgpu-unroll-max-block-to-analyze",
cl::desc("Inner loop block size threshold to analyze in unroll for AMDGPU"),
cl::init(20), cl::Hidden);
cl::init(32), cl::Hidden);
static bool dependsOnLocalPhi(const Loop *L, const Value *Cond,
unsigned Depth = 0) {

43
test/Transforms/LoopUnroll/AMDGPU/unroll-analyze-small-loops.ll
View File

@ -1,8 +1,9 @@
; RUN: opt -S -mtriple=amdgcn-unknown-amdhsa -loop-unroll -unroll-threshold=150 < %s | FileCheck %s
; RUN: opt -S -mtriple=amdgcn-unknown-amdhsa -loop-unroll < %s | FileCheck %s
; Test that max iterations count to analyze (specific for the target)
; is enough to make the inner loop completely unrolled
define hidden void @foo(float addrspace(1)* %ptrG, float addrspace(3)* %ptrL, i32 %A, i32 %A2, i32 %M) {
; CHECK-LABEL: foo
define void @foo(float addrspace(5)* %ptrB, float addrspace(5)* %ptrC, i32 %A, i32 %A2, float %M) {
bb:
br label %bb2
@ -28,22 +29,28 @@ bb10: ; preds = %for.body
%cmpj = icmp ult i32 %i11, 8
br i1 %cmpj, label %bb7, label %bb4
; CHECK: for.body:
; CHECK-LABEL: for.body
; CHECK-NOT: %phi = phi {{.*}}
for.body: ; preds = %for.body, %bb4
%phi = phi i32 [ 0, %bb4 ], [ %k, %for.body ]
%mul = shl nuw nsw i32 %phi, 5
%add1 = add i32 %A, %mul
%add2 = add i32 %add1, %M
%arrayidx = getelementptr inbounds float, float addrspace(3)* %ptrL, i32 %add2
%bc = bitcast float addrspace(3)* %arrayidx to i32 addrspace(3)*
%ld = load i32, i32 addrspace(3)* %bc, align 4
for.body: ; preds = %bb4, %for.body
%phi = phi i32 [ 0, %bb4 ], [ %inc, %for.body ]
%mul = shl nuw nsw i32 %phi, 6
%add = add i32 %A, %mul
%arrayidx = getelementptr inbounds float, float addrspace(5)* %ptrC, i32 %add
%ld1 = load float, float addrspace(5)* %arrayidx, align 4
%mul2 = shl nuw nsw i32 %phi, 3
%add3 = add nuw nsw i32 %mul2, %A2
%arrayidx2 = getelementptr inbounds float, float addrspace(1)* %ptrG, i32 %add3
%bc2 = bitcast float addrspace(1)* %arrayidx2 to i32 addrspace(1)*
store i32 %ld, i32 addrspace(1)* %bc2, align 4
%k = add nuw nsw i32 %phi, 1
%cmpk = icmp ult i32 %k, 32
br i1 %cmpk, label %for.body, label %bb10
%add2 = add i32 %A2, %mul2
%arrayidx2 = getelementptr inbounds float, float addrspace(5)* %ptrB, i32 %add2
%ld2 = load float, float addrspace(5)* %arrayidx2, align 4
%mul3 = fmul contract float %M, %ld2
%add3 = fadd contract float %ld1, %mul3
store float %add3, float addrspace(5)* %arrayidx, align 4
%add1 = add nuw nsw i32 %add, 2048
%arrayidx3 = getelementptr inbounds float, float addrspace(5)* %ptrC, i32 %add1
%ld3 = load float, float addrspace(5)* %arrayidx3, align 4
%mul4 = fmul contract float %ld2, %M
%add4 = fadd contract float %ld3, %mul4
store float %add4, float addrspace(5)* %arrayidx3, align 4
%inc = add nuw nsw i32 %phi, 1
%cmpi = icmp ult i32 %phi, 31
br i1 %cmpi, label %for.body, label %bb10
}