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119003f2a2
Fixes rdar:13349374. Volatile loads and stores need to be preserved even if the language standard says they are undefined. "volatile" in this context means "get out of the way compiler, let my platform handle it". Additionally, this is the only way I know of with llvm to write to the first page (when hardware allows) without dropping to assembly. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176599 91177308-0d34-0410-b5e6-96231b3b80d8
49 lines
1.9 KiB
LLVM
49 lines
1.9 KiB
LLVM
; RUN: opt < %s -simplifycfg -S | FileCheck %s
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;
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; rdar:13349374
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;
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; SimplifyCFG should not eliminate blocks with volatile stores.
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; Essentially, volatile needs to be backdoor that tells the optimizer
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; it can no longer use language standard as an excuse. The compiler
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; needs to expose the volatile access to the platform.
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;
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; CHECK: @test
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; CHECK: entry:
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; CHECK: @Trace
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; CHECK: while.body:
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; CHECK: store volatile
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; CHECK: end:
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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-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
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define void @test(i8** nocapture %PeiServices) #0 {
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entry:
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%call = tail call i32 (...)* @Trace() #2
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%tobool = icmp eq i32 %call, 0
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br i1 %tobool, label %while.body, label %if.then
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if.then: ; preds = %entry
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%call1 = tail call i32 (...)* @Trace() #2
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br label %while.body
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while.body: ; preds = %entry, %if.then, %while.body
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%Addr.017 = phi i8* [ %incdec.ptr, %while.body ], [ null, %if.then ], [ null, %entry ]
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%x.016 = phi i8 [ %inc, %while.body ], [ 0, %if.then ], [ 0, %entry ]
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%inc = add i8 %x.016, 1
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%incdec.ptr = getelementptr inbounds i8* %Addr.017, i64 1
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store volatile i8 %x.016, i8* %Addr.017, align 1
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%0 = ptrtoint i8* %incdec.ptr to i64
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%1 = trunc i64 %0 to i32
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%cmp = icmp ult i32 %1, 4096
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br i1 %cmp, label %while.body, label %end
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end:
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ret void
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}
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declare i32 @Trace(...) #1
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attributes #0 = { nounwind ssp uwtable "fp-contract-model"="standard" "no-frame-pointer-elim" "no-frame-pointer-elim-non-leaf" "realign-stack" "relocation-model"="pic" "ssp-buffers-size"="8" }
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attributes #1 = { "fp-contract-model"="standard" "no-frame-pointer-elim" "no-frame-pointer-elim-non-leaf" "realign-stack" "relocation-model"="pic" "ssp-buffers-size"="8" }
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attributes #2 = { nounwind }
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!0 = metadata !{i32 1039}
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