llvm/test/Transforms/CodeGenPrepare/basic.ll
Nadav Rotem 3e883734fa During the CodeGenPrepare we often lower intrinsics (such as objsize)
and allow some optimizations to turn conditional branches into unconditional.
This commit adds a simple control-flow optimization which merges two consecutive
basic blocks which are connected by a single edge. This allows the codegen to
operate on larger basic blocks.

rdar://11973998



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161852 91177308-0d34-0410-b5e6-96231b3b80d8
2012-08-14 05:19:07 +00:00

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LLVM

; RUN: opt -codegenprepare %s -S -o - | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
target triple = "x86_64-apple-darwin10.0.0"
; CHECK: @test1
; objectsize should fold to a constant, which causes the branch to fold to an
; uncond branch. Next, we fold the control flow alltogether.
; rdar://8785296
define i32 @test1(i8* %ptr) nounwind ssp noredzone align 2 {
entry:
%0 = tail call i64 @llvm.objectsize.i64(i8* %ptr, i1 false)
%1 = icmp ugt i64 %0, 3
br i1 %1, label %T, label %trap
; CHECK: T:
; CHECK-NOT: br label %
trap: ; preds = %0, %entry
tail call void @llvm.trap() noreturn nounwind
unreachable
T:
; CHECK: ret i32 4
ret i32 4
}
declare i64 @llvm.objectsize.i64(i8*, i1) nounwind readonly
declare void @llvm.trap() nounwind