[LLVMbugs] [Bug 20405] New: tailcallelim incorrectly marks calls as tail if stack is leaked by writing through a function argument

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=20405

            Bug ID: 20405
           Summary: tailcallelim incorrectly marks calls as tail if stack
                    is leaked by writing through a function argument
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: release blocker
          Priority: P
         Component: Scalar Optimizations
          Assignee: nlewycky at google.com
          Reporter: richard-llvm at metafoo.co.uk
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

tailcallelim marks both calls to @foo in this testcase as 'tail'. It should
not; @hoge leaks a pointer to the stack. (It should still mark @pluto as
'tail', though.)


; ModuleID = 'tmp4.ll'
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-grtev3-linux-gnu"

%struct.barney = type { %struct.hoge }
%struct.hoge = type { i32 (...)**, %struct.hoge.0 }
%struct.hoge.0 = type { %struct.widget }
%struct.widget = type { %struct.eggs }
%struct.eggs = type { %struct.pluto* }
%struct.pluto = type { %struct.wombat* }
%struct.wombat = type opaque
%struct.spam = type { %struct.zot }
%struct.zot = type { %struct.wobble }
%struct.wobble = type { i32*, i64 }

@global = external thread_local(initialexec) global [1000 x i64]

; Function Attrs: nounwind sanitize_memory uwtable
define void @zot(%struct.barney* nocapture readnone %arg) unnamed_addr #0 align
2 {
bb:
  %tmp = alloca %struct.spam, align 8
  %tmp1 = alloca %struct.spam, align 8
  %tmp2 = alloca [1 x i32], align 4
  %tmp3 = alloca %struct.spam, align 8
  %tmp4 = alloca [4 x i32], align 4
  call void @baz(%struct.spam* %tmp)
  %tmp5 = getelementptr inbounds %struct.spam* %tmp, i64 0, i32 0, i32 0, i32 0
  %tmp6 = load i32** %tmp5, align 8
  %tmp7 = getelementptr %struct.spam* %tmp, i64 0, i32 0, i32 0, i32 1
  %tmp8 = load i64* %tmp7, align 8
  call fastcc void @pluto(i32* %tmp6, i64 %tmp8)
  %tmp9 = getelementptr inbounds [1 x i32]* %tmp2, i64 0, i64 0
  store i32 1, i32* %tmp9, align 4
  call void @hoge(%struct.spam* %tmp1, i32* %tmp9, i64 1)
  %tmp10 = getelementptr inbounds %struct.spam* %tmp1, i64 0, i32 0, i32 0, i32
0
  %tmp11 = load i32** %tmp10, align 8
  %tmp12 = getelementptr %struct.spam* %tmp1, i64 0, i32 0, i32 0, i32 1
  %tmp13 = load i64* %tmp12, align 8
  call fastcc void @foo(i32* %tmp11, i64 %tmp13, i32 1, i32 1)
  %tmp14 = getelementptr inbounds [4 x i32]* %tmp4, i64 0, i64 0
  store i32 10, i32* %tmp14, align 4
  %tmp15 = getelementptr inbounds [4 x i32]* %tmp4, i64 0, i64 1
  store i32 11, i32* %tmp15, align 4
  %tmp16 = getelementptr inbounds [4 x i32]* %tmp4, i64 0, i64 2
  store i32 12, i32* %tmp16, align 4
  %tmp17 = getelementptr inbounds [4 x i32]* %tmp4, i64 0, i64 3
  store i32 13, i32* %tmp17, align 4
  call void @hoge(%struct.spam* %tmp3, i32* %tmp14, i64 4)
  %tmp18 = getelementptr inbounds %struct.spam* %tmp3, i64 0, i32 0, i32 0, i32
0
  %tmp19 = load i32** %tmp18, align 8
  %tmp20 = getelementptr %struct.spam* %tmp3, i64 0, i32 0, i32 0, i32 1
  %tmp21 = load i64* %tmp20, align 8
  call fastcc void @foo(i32* %tmp19, i64 %tmp21, i32 10, i32 13)
  ret void
}

; Function Attrs: nounwind sanitize_memory uwtable
declare hidden void @pluto(i32*, i64) #0

; Function Attrs: nounwind sanitize_memory uwtable
declare void @baz(%struct.spam* nocapture) unnamed_addr #0 align 2

; Function Attrs: nounwind sanitize_memory uwtable
declare hidden void @foo(i32*, i64, i32, i32) #0

; Function Attrs: nounwind sanitize_memory uwtable
declare void @hoge(%struct.spam* nocapture, i32*, i64) unnamed_addr #0 align 2

; Function Attrs: nounwind
declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1) #1

attributes #0 = { nounwind sanitize_memory uwtable "less-precise-fpmad"="false"
"no-frame-pointer-elim"="false" "no-frame-pointer-elim-non-leaf"
"no-infs-fp-math"="false" "no-nans-fp-math"="false"
"stack-protector-buffer-size"="8" "unsafe-fp-math"="false"
"use-soft-float"="false" }
attributes #1 = { nounwind }

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