[PATCH] D17542: Disallow generating vzeroupper before return instruction (iret) in interrupt handler function

[Nadav Rotem via llvm-commits]

The patch LGTM. 

Can you please move the comment above the line? I think it would make the code easier to follow. 



> On Feb 23, 2016, at 06:27, Amjad Aboud <amjad.aboud at intel.com> wrote:
> 
> aaboud created this revision.
> aaboud added reviewers: DavidKreitzer, hjl.tools, nadav.
> aaboud added a subscriber: llvm-commits.
> 
> Resolved Bug 26412.
> https://llvm.org/bugs/show_bug.cgi?id=26412
> 
> 
> http://reviews.llvm.org/D17542
> 
> Files:
>  lib/Target/X86/X86VZeroUpper.cpp
>  test/CodeGen/X86/x86-interrupt_vzeroupper.ll
> 
> Index: lib/Target/X86/X86VZeroUpper.cpp
> ===================================================================
> --- lib/Target/X86/X86VZeroUpper.cpp
> +++ lib/Target/X86/X86VZeroUpper.cpp
> @@ -80,6 +80,7 @@
>     BlockStateMap BlockStates;
>     DirtySuccessorsWorkList DirtySuccessors;
>     bool EverMadeChange;
> +    bool IsX86INTR;
>     const TargetInstrInfo *TII;
> 
>     static char ID;
> @@ -181,7 +182,11 @@
> 
>   for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ++I) {
>     MachineInstr *MI = I;
> -    bool isControlFlow = MI->isCall() || MI->isReturn();
> +    bool isControlFlow = MI->isCall() ||
> +                         // No need for vzeroupper before iret in interrupt
> +                         // handler function, epilogue will restore YMM
> +                         // registers if needed.
> +                         (MI->isReturn() && !IsX86INTR);
> 
>     // Shortcut: don't need to check regular instructions in dirty state.
>     if (!isControlFlow && CurState == EXITS_DIRTY)
> @@ -253,6 +258,7 @@
>   TII = ST.getInstrInfo();
>   MachineRegisterInfo &MRI = MF.getRegInfo();
>   EverMadeChange = false;
> +  IsX86INTR = MF.getFunction()->getCallingConv() == CallingConv::X86_INTR;
> 
>   bool FnHasLiveInYmm = checkFnHasLiveInYmm(MRI);
> 
> Index: test/CodeGen/X86/x86-interrupt_vzeroupper.ll
> ===================================================================
> --- test/CodeGen/X86/x86-interrupt_vzeroupper.ll
> +++ test/CodeGen/X86/x86-interrupt_vzeroupper.ll
> @@ -0,0 +1,41 @@
> +; RUN: llc -mtriple=x86_64-unknown-unknown < %s | FileCheck %s
> +
> +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> +;; Checks that interrupt handler code does not call "vzeroupper" instruction
> +;; before iret.
> +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> +;; Command line: -Wall -march=nehalem -S -o - -emit-llvm -O2
> +;; Source:
> +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> +;;extern void foo (void *) __attribute__ ((interrupt));
> +;;extern void bar (void);
> +;;
> +;;void foo (void *frame)
> +;;{
> +;;  bar ();
> +;;}
> +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> +
> +; CHECK: vzeroupper
> +; CHECK-NEXT: call
> +; CHECK-NOT: vzeroupper
> +; CHECK: iret
> +
> + at llvm.used = appending global [1 x i8*] [i8* bitcast (void (i8*)* @foo to i8*)], section "llvm.metadata"
> +
> +; Function Attrs: nounwind uwtable
> +define x86_intrcc void @foo(i8* nocapture readnone %frame) #0 {
> +entry:
> +  tail call void @bar() #2
> +  ret void
> +}
> +
> +declare void @bar() #1
> +
> +attributes #0 = { nounwind uwtable "disable-tail-calls"="true" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "stackrealign" "target-cpu"="nehalem" "target-features"="+avx,+cx16,+fxsr,+popcnt,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+xsave,-3dnow,-3dnowa,-mmx" "unsafe-fp-math"="false" "use-soft-float"="true" }
> +attributes #1 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="nehalem" "target-features"="+avx,+cx16,+fxsr,+mmx,+popcnt,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+xsave" "unsafe-fp-math"="false" "use-soft-float"="false" }
> +attributes #2 = { nounwind }
> +
> +!llvm.ident = !{!0}
> +
> +!0 = !{!"clang version 3.9.0 (trunk 259349) (llvm/trunk 259357)"}
> 
> 
> <D17542.48814.patch>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20160223/12a4fe03/attachment.html>