ae05b9dc30
Currently, instructions in the preheader of the second of two fusion candidates are sunk and hoisted whenever possible, to try to allow the loops to fuse. Memory instructions are skipped, and are never sunk or hoisted. This change adds memory instructions for sinking/hoisting consideration. This change uses DependenceAnalysis to check if a mem inst in the preheader of FC1 depends on an instruction in FC0's header, across which it will be hoisted, or FC1's header, across which it will be sunk. We reject cases where the dependency is a data hazard. Differential Revision: https://reviews.llvm.org/D131606
49 lines
1.6 KiB
LLVM
49 lines
1.6 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -S -loop-simplify -loop-fusion -debug-only=loop-fusion < %s 2>&1 | FileCheck %s
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; REQUIRES: asserts
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; CHECK: Safe to sink.
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@A = common global [100 x i32] zeroinitializer, align 16
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define void @sink_preheader(i32 %N) {
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; CHECK-LABEL: @sink_preheader(
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; CHECK-NEXT: pre1:
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; CHECK-NEXT: [[PTR:%.*]] = alloca i32, align 4
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; CHECK-NEXT: br label [[BODY1:%.*]]
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; CHECK: body1:
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; CHECK-NEXT: [[I:%.*]] = phi i32 [ [[I_NEXT:%.*]], [[BODY1]] ], [ 0, [[PRE1:%.*]] ]
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; CHECK-NEXT: [[I2:%.*]] = phi i32 [ [[I_NEXT2:%.*]], [[BODY1]] ], [ 0, [[PRE1]] ]
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; CHECK-NEXT: [[I_NEXT]] = add i32 1, [[I]]
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; CHECK-NEXT: [[COND:%.*]] = icmp ne i32 [[I]], [[N:%.*]]
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; CHECK-NEXT: store i32 3, i32* [[PTR]], align 4
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; CHECK-NEXT: [[I_NEXT2]] = add i32 1, [[I2]]
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; CHECK-NEXT: [[COND2:%.*]] = icmp ne i32 [[I2]], [[N]]
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; CHECK-NEXT: br i1 [[COND2]], label [[BODY1]], label [[EXIT:%.*]]
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; CHECK: exit:
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; CHECK-NEXT: [[B:%.*]] = load i32, i32* [[PTR]], align 4
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; CHECK-NEXT: ret void
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;
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pre1:
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%ptr = alloca i32
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br label %body1
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body1: ; preds = %pre1, %body1
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%i = phi i32 [%i_next, %body1], [0, %pre1]
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%i_next = add i32 1, %i
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%cond = icmp ne i32 %i, %N
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store i32 3, i32* %ptr
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br i1 %cond, label %body1, label %pre2
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pre2:
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%b = load i32, i32 * %ptr
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br label %body2
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body2: ; preds = %pre2, %body2
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%i2 = phi i32 [%i_next2, %body2], [0, %pre2]
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%i_next2 = add i32 1, %i2
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%cond2 = icmp ne i32 %i2, %N
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br i1 %cond2, label %body2, label %exit
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exit:
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ret void
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}
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