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https://github.com/c64scene-ar/llvm-6502.git
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6d31268a7d
to break up CFG diamonds by banishing one of the blocks to the end of the function, which is bad for code density and branch size. This does pessimize MultiSource/Benchmarks/Ptrdist/yacr2, the benchmark cited as the reason for the change, however I've examined the code and it looks more like a case of gaming a particular branch than of being generally applicable. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84803 91177308-0d34-0410-b5e6-96231b3b80d8
208 lines
4.4 KiB
LLVM
208 lines
4.4 KiB
LLVM
; RUN: llc < %s -march=x86-64 -mtriple=x86_64-unknown-linux-gnu -asm-verbose=false | FileCheck %s
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; These tests check for loop branching structure, and that the loop align
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; directive is placed in the expected place.
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; CodeGen should insert a branch into the middle of the loop in
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; order to avoid a branch within the loop.
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; CHECK: simple:
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; CHECK: jmp .LBB1_1
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; CHECK-NEXT: align
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; CHECK-NEXT: .LBB1_2:
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; CHECK-NEXT: call loop_latch
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; CHECK-NEXT: .LBB1_1:
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; CHECK-NEXT: call loop_header
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define void @simple() nounwind {
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entry:
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br label %loop
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loop:
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call void @loop_header()
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%t0 = tail call i32 @get()
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%t1 = icmp slt i32 %t0, 0
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br i1 %t1, label %done, label %bb
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bb:
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call void @loop_latch()
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br label %loop
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done:
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call void @exit()
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ret void
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}
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; CodeGen should move block_a to the top of the loop so that it
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; falls through into the loop, avoiding a branch within the loop.
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; CHECK: slightly_more_involved:
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; CHECK: jmp .LBB2_1
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; CHECK-NEXT: align
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; CHECK-NEXT: .LBB2_4:
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; CHECK-NEXT: call bar99
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; CHECK-NEXT: .LBB2_1:
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; CHECK-NEXT: call body
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define void @slightly_more_involved() nounwind {
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entry:
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br label %loop
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loop:
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call void @body()
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%t0 = call i32 @get()
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%t1 = icmp slt i32 %t0, 2
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br i1 %t1, label %block_a, label %bb
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bb:
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%t2 = call i32 @get()
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%t3 = icmp slt i32 %t2, 99
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br i1 %t3, label %exit, label %loop
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block_a:
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call void @bar99()
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br label %loop
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exit:
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call void @exit()
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ret void
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}
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; Same as slightly_more_involved, but block_a is now a CFG diamond with
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; fallthrough edges which should be preserved.
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; CHECK: yet_more_involved:
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; CHECK: jmp .LBB3_1
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; CHECK-NEXT: align
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; CHECK-NEXT: .LBB3_3:
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; CHECK-NEXT: call bar99
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; CHECK-NEXT: call get
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; CHECK-NEXT: cmpl $2999, %eax
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; CHECK-NEXT: jg .LBB3_5
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; CHECK-NEXT: call block_a_true_func
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; CHECK-NEXT: jmp .LBB3_6
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; CHECK-NEXT: .LBB3_5:
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; CHECK-NEXT: call block_a_false_func
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; CHECK-NEXT: .LBB3_6:
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; CHECK-NEXT: call block_a_merge_func
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; CHECK-NEXT: .LBB3_1:
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; CHECK-NEXT: call body
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define void @yet_more_involved() nounwind {
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entry:
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br label %loop
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loop:
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call void @body()
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%t0 = call i32 @get()
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%t1 = icmp slt i32 %t0, 2
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br i1 %t1, label %block_a, label %bb
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bb:
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%t2 = call i32 @get()
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%t3 = icmp slt i32 %t2, 99
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br i1 %t3, label %exit, label %loop
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block_a:
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call void @bar99()
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%z0 = call i32 @get()
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%z1 = icmp slt i32 %z0, 3000
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br i1 %z1, label %block_a_true, label %block_a_false
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block_a_true:
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call void @block_a_true_func()
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br label %block_a_merge
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block_a_false:
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call void @block_a_false_func()
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br label %block_a_merge
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block_a_merge:
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call void @block_a_merge_func()
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br label %loop
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exit:
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call void @exit()
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ret void
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}
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; CodeGen should move the CFG islands that are part of the loop but don't
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; conveniently fit anywhere so that they are at least contiguous with the
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; loop.
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; CHECK: cfg_islands:
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; CHECK: jmp .LBB4_1
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; CHECK-NEXT: align
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; CHECK-NEXT: .LBB4_7:
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; CHECK-NEXT: call bar100
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; CHECK-NEXT: jmp .LBB4_1
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; CHECK-NEXT: .LBB4_8:
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; CHECK-NEXT: call bar101
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; CHECK-NEXT: jmp .LBB4_1
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; CHECK-NEXT: .LBB4_9:
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; CHECK-NEXT: call bar102
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; CHECK-NEXT: jmp .LBB4_1
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; CHECK-NEXT: .LBB4_5:
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; CHECK-NEXT: call loop_latch
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; CHECK-NEXT: .LBB4_1:
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; CHECK-NEXT: call loop_header
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define void @cfg_islands() nounwind {
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entry:
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br label %loop
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loop:
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call void @loop_header()
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%t0 = call i32 @get()
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%t1 = icmp slt i32 %t0, 100
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br i1 %t1, label %block100, label %bb
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bb:
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%t2 = call i32 @get()
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%t3 = icmp slt i32 %t2, 101
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br i1 %t3, label %block101, label %bb1
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bb1:
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%t4 = call i32 @get()
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%t5 = icmp slt i32 %t4, 102
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br i1 %t5, label %block102, label %bb2
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bb2:
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%t6 = call i32 @get()
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%t7 = icmp slt i32 %t6, 103
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br i1 %t7, label %exit, label %bb3
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bb3:
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call void @loop_latch()
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br label %loop
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exit:
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call void @exit()
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ret void
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block100:
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call void @bar100()
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br label %loop
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block101:
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call void @bar101()
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br label %loop
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block102:
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call void @bar102()
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br label %loop
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}
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declare void @bar99() nounwind
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declare void @bar100() nounwind
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declare void @bar101() nounwind
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declare void @bar102() nounwind
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declare void @body() nounwind
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declare void @exit() nounwind
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declare void @loop_header() nounwind
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declare void @loop_latch() nounwind
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declare i32 @get() nounwind
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declare void @block_a_true_func() nounwind
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declare void @block_a_false_func() nounwind
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declare void @block_a_merge_func() nounwind
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