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https://github.com/c64scene-ar/llvm-6502.git
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5ee67e8e76
PowerPC has a conditional branch to the link register (return) instruction: BCLR. This should be used any time when we'd otherwise have a conditional branch to a return. This adds a small pass, PPCEarlyReturn, which runs just prior to the branch selection pass (and, importantly, after block placement) to generate these conditional returns when possible. It will also eliminate unconditional branches to returns (these happen rarely; most of the time these have already been tail duplicated by the time PPCEarlyReturn is invoked). This is a nice optimization for small functions that do not maintain a stack frame. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179026 91177308-0d34-0410-b5e6-96231b3b80d8
53 lines
1.5 KiB
LLVM
53 lines
1.5 KiB
LLVM
; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 | FileCheck %s
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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-f128:128:128-v128:128:128-n32:64"
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target triple = "powerpc64-unknown-linux-gnu"
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define void @foo(i32* %P) #0 {
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entry:
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%tobool = icmp eq i32* %P, null
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br i1 %tobool, label %if.end, label %if.then
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if.then: ; preds = %entry
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store i32 0, i32* %P, align 4, !tbaa !0
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br label %if.end
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if.end: ; preds = %entry, %if.then
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ret void
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; CHECK: @foo
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; CHECK: beqlr
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; CHECK: blr
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}
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define void @bar(i32* %P, i32* %Q) #0 {
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entry:
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%tobool = icmp eq i32* %P, null
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br i1 %tobool, label %if.else, label %if.then
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if.then: ; preds = %entry
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store i32 0, i32* %P, align 4, !tbaa !0
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%tobool1 = icmp eq i32* %Q, null
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br i1 %tobool1, label %if.end3, label %if.then2
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if.then2: ; preds = %if.then
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store i32 1, i32* %Q, align 4, !tbaa !0
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br label %if.end3
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if.else: ; preds = %entry
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store i32 0, i32* %Q, align 4, !tbaa !0
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br label %if.end3
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if.end3: ; preds = %if.then, %if.then2, %if.else
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ret void
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; CHECK: @bar
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; CHECK: beqlr
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; CHECK: blr
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}
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attributes #0 = { nounwind }
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!0 = metadata !{metadata !"int", metadata !1}
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!1 = metadata !{metadata !"omnipotent char", metadata !2}
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!2 = metadata !{metadata !"Simple C/C++ TBAA"}
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