[llvm] [LoopUnroll] Consider simplified operands while retrieving TTI instruction cost (PR #70929)
Sergey Kachkov via llvm-commits
llvm-commits at lists.llvm.org
Wed Nov 1 07:26:12 PDT 2023
https://github.com/skachkov-sc updated https://github.com/llvm/llvm-project/pull/70929
>From 1b6cdeffa9c863f3224dc1ef1ff561a94ad20a28 Mon Sep 17 00:00:00 2001
From: Sergey Kachkov <sergey.kachkov at syntacore.com>
Date: Mon, 30 Oct 2023 12:28:14 +0300
Subject: [PATCH 1/3] [LoopUnroll][NFC] Add pre-commit test
---
.../Transforms/LoopUnroll/RISCV/unroll-Os.ll | 35 +++++++++++++++++++
1 file changed, 35 insertions(+)
create mode 100644 llvm/test/Transforms/LoopUnroll/RISCV/unroll-Os.ll
diff --git a/llvm/test/Transforms/LoopUnroll/RISCV/unroll-Os.ll b/llvm/test/Transforms/LoopUnroll/RISCV/unroll-Os.ll
new file mode 100644
index 000000000000000..d94cba659051f17
--- /dev/null
+++ b/llvm/test/Transforms/LoopUnroll/RISCV/unroll-Os.ll
@@ -0,0 +1,35 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
+; RUN: opt < %s -S -mtriple=riscv64 -passes=loop-unroll | FileCheck %s
+
+; Function Attrs: optsize
+define void @foo(ptr %array, i32 %x) #0 {
+; CHECK-LABEL: define void @foo
+; CHECK-SAME: (ptr [[ARRAY:%.*]], i32 [[X:%.*]]) #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[FOR_BODY:%.*]]
+; CHECK: for.body:
+; CHECK-NEXT: [[INDVARS_IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDVARS_IV_NEXT:%.*]], [[FOR_BODY]] ]
+; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds i32, ptr [[ARRAY]], i64 [[INDVARS_IV]]
+; CHECK-NEXT: store i32 [[X]], ptr [[ARRAYIDX]], align 4
+; CHECK-NEXT: [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 1
+; CHECK-NEXT: [[EXITCOND_NOT:%.*]] = icmp eq i64 [[INDVARS_IV_NEXT]], 4
+; CHECK-NEXT: br i1 [[EXITCOND_NOT]], label [[FOR_COND_CLEANUP:%.*]], label [[FOR_BODY]]
+; CHECK: for.cond.cleanup:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %for.body
+
+for.body:
+ %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+ %arrayidx = getelementptr inbounds i32, ptr %array, i64 %indvars.iv
+ store i32 %x, ptr %arrayidx, align 4
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ %exitcond.not = icmp eq i64 %indvars.iv.next, 4
+ br i1 %exitcond.not, label %for.cond.cleanup, label %for.body
+
+for.cond.cleanup:
+ ret void
+}
+
+attributes #0 = { optsize }
>From f89182079d9640ba1a87b37461d2a79cabe2ff1d Mon Sep 17 00:00:00 2001
From: Sergey Kachkov <sergey.kachkov at syntacore.com>
Date: Fri, 27 Oct 2023 19:35:20 +0300
Subject: [PATCH 2/3] [LoopUnroll] Consider simplified operands while
retrieving TTI instruction cost
Get more precise cost of instruction after LoopUnroll considering that
some operands of it can be simplified, e.g. induction variable will be
replaced by constant after full unrolling.
---
llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp | 10 +++++++++-
llvm/test/Transforms/LoopUnroll/RISCV/unroll-Os.ll | 14 +++++++-------
2 files changed, 16 insertions(+), 8 deletions(-)
diff --git a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
index 446aa497026d3fb..470bc3038669d83 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -443,7 +443,15 @@ static std::optional<EstimatedUnrollCost> analyzeLoopUnrollCost(
// First accumulate the cost of this instruction.
if (!Cost.IsFree) {
- UnrolledCost += TTI.getInstructionCost(I, CostKind);
+ // Consider simplified operands in instruction cost.
+ SmallVector<Value *, 4> Operands;
+ transform(I->operands(), std::back_inserter(Operands),
+ [&](Value *Op) {
+ if (auto Res = SimplifiedValues.lookup(Op))
+ return Res;
+ return Op;
+ });
+ UnrolledCost += TTI.getInstructionCost(I, Operands, CostKind);
LLVM_DEBUG(dbgs() << "Adding cost of instruction (iteration "
<< Iteration << "): ");
LLVM_DEBUG(I->dump());
diff --git a/llvm/test/Transforms/LoopUnroll/RISCV/unroll-Os.ll b/llvm/test/Transforms/LoopUnroll/RISCV/unroll-Os.ll
index d94cba659051f17..26de40bf1dc13e4 100644
--- a/llvm/test/Transforms/LoopUnroll/RISCV/unroll-Os.ll
+++ b/llvm/test/Transforms/LoopUnroll/RISCV/unroll-Os.ll
@@ -8,13 +8,13 @@ define void @foo(ptr %array, i32 %x) #0 {
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
-; CHECK-NEXT: [[INDVARS_IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDVARS_IV_NEXT:%.*]], [[FOR_BODY]] ]
-; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds i32, ptr [[ARRAY]], i64 [[INDVARS_IV]]
-; CHECK-NEXT: store i32 [[X]], ptr [[ARRAYIDX]], align 4
-; CHECK-NEXT: [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 1
-; CHECK-NEXT: [[EXITCOND_NOT:%.*]] = icmp eq i64 [[INDVARS_IV_NEXT]], 4
-; CHECK-NEXT: br i1 [[EXITCOND_NOT]], label [[FOR_COND_CLEANUP:%.*]], label [[FOR_BODY]]
-; CHECK: for.cond.cleanup:
+; CHECK-NEXT: store i32 [[X]], ptr [[ARRAY]], align 4
+; CHECK-NEXT: [[ARRAYIDX_1:%.*]] = getelementptr inbounds i32, ptr [[ARRAY]], i64 1
+; CHECK-NEXT: store i32 [[X]], ptr [[ARRAYIDX_1]], align 4
+; CHECK-NEXT: [[ARRAYIDX_2:%.*]] = getelementptr inbounds i32, ptr [[ARRAY]], i64 2
+; CHECK-NEXT: store i32 [[X]], ptr [[ARRAYIDX_2]], align 4
+; CHECK-NEXT: [[ARRAYIDX_3:%.*]] = getelementptr inbounds i32, ptr [[ARRAY]], i64 3
+; CHECK-NEXT: store i32 [[X]], ptr [[ARRAYIDX_3]], align 4
; CHECK-NEXT: ret void
;
entry:
>From e719131ba680f5b275d926e2f3c0bf83ef01e78c Mon Sep 17 00:00:00 2001
From: Sergey Kachkov <sergey.kachkov at syntacore.com>
Date: Wed, 1 Nov 2023 17:24:40 +0300
Subject: [PATCH 3/3] Fix AMDPGU test
---
.../Transforms/LoopUnroll/AMDGPU/unroll-cost-addrspacecast.ll | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/llvm/test/Transforms/LoopUnroll/AMDGPU/unroll-cost-addrspacecast.ll b/llvm/test/Transforms/LoopUnroll/AMDGPU/unroll-cost-addrspacecast.ll
index 6ec64bfba895961..a23ce841dc88223 100644
--- a/llvm/test/Transforms/LoopUnroll/AMDGPU/unroll-cost-addrspacecast.ll
+++ b/llvm/test/Transforms/LoopUnroll/AMDGPU/unroll-cost-addrspacecast.ll
@@ -50,7 +50,7 @@ for.end:
}
; CHECK-LABEL: @test_func_addrspacecast_cost_nonfree(
-; CHECK: br i1 %exitcond
+; CHECK-NOT: br i1 %exitcond
define amdgpu_kernel void @test_func_addrspacecast_cost_nonfree(ptr addrspace(3) noalias nocapture %out, ptr addrspace(3) noalias nocapture %in) #0 {
entry:
br label %for.body
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