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f5fe960ebc
Merging identical blocks when it doesn't reduce fallthrough. It is common for the blocks created from critical edge splitting to be identical. We would like to merge these blocks whenever doing so would not reduce fallthrough. llvm-svn: 299890
42 lines
1.5 KiB
LLVM
42 lines
1.5 KiB
LLVM
; RUN: llc -o - -verify-machineinstrs %s | FileCheck %s
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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@data = external global [3 x i32], align 4
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@store = external global i32, align 4
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; %else1 and %then2 end up lowering to identical blocks. These blocks should be
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; merged during tail-merging.
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; CHECK-LABEL: merge_identical_blocks
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; CHECK: movl $data+4
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; CHECK-NOT: movl $data+4
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; CHECK: retq
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define void @merge_identical_blocks(i1 %a, i1 %b) {
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entry:
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br label %if1
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if1: ; predfs = %entry
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br i1 %a, label %else1, label %if2
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else1: ; preds = %if1
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%ptr.else1 = getelementptr inbounds [3 x i32], [3 x i32]* @data, i64 0, i32 1
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br label %phi_join
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if2: ; preds = %if1
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br i1 %b, label %then2, label %else2
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then2: ; preds = %if2
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%ptr.then2 = getelementptr inbounds [3 x i32], [3 x i32]* @data, i64 0, i32 1
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br label %phi_join
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else2: ; preds = %if2
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%ptr.else2 = getelementptr inbounds [3 x i32], [3 x i32]* @data, i64 0, i32 2
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br label %phi_join
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phi_join: ; preds = %else1, %then2, %else2
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%val.ptr = phi i32* [ %ptr.else1, %else1 ], [ %ptr.then2, %then2 ], [ %ptr.else2, %else2 ]
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%val = load i32, i32* %val.ptr, align 4
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store i32 %val, i32* @store, align 4
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ret void
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}
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