[llvm] r323559 - [LivePhysRegs] Preserve pristine regs in blocks with no successors.

[Galina Kistanova via llvm-commits]

Hello Eli,

This commit broke the test LLVM :: CodeGen/ARM/pr25838.ll on one of our
builders:
r323559
http://lab.llvm.org:8011/builders/llvm-clang-x86_64-expensive-checks-win/builds/7546

. . .
Failing Tests (2):
    LLVM :: CodeGen/ARM/pr25838.ll
    LLVM :: DebugInfo/Generic/string-offsets-multiple-cus.ll

Previous revision:
http://lab.llvm.org:8011/builders/llvm-clang-x86_64-expensive-checks-win/builds/7610

Please have a look?

Thanks

Galina


On Fri, Jan 26, 2018 at 12:23 PM, Eli Friedman via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: efriedma
> Date: Fri Jan 26 12:23:00 2018
> New Revision: 323559
>
> URL: http://llvm.org/viewvc/llvm-project?rev=323559&view=rev
> Log:
> [LivePhysRegs] Preserve pristine regs in blocks with no successors.
>
> One common source of blocks with no successors is calls to noreturn
> functions; we want to preserve pristine registers in case they throw an
> exception.
>
> The whole pristine register thing is messy (we should really prefer to
> explicitly model registers), but this fills a hole in the model for now.
>
> Fixes https://bugs.llvm.org/show_bug.cgi?id=36073.
>
> Differential Revision: https://reviews.llvm.org/D42509
>
>
> Added:
>     llvm/trunk/test/CodeGen/Thumb/stm-scavenging.ll
> Modified:
>     llvm/trunk/lib/CodeGen/LivePhysRegs.cpp
>
> Modified: llvm/trunk/lib/CodeGen/LivePhysRegs.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
> CodeGen/LivePhysRegs.cpp?rev=323559&r1=323558&r2=323559&view=diff
> ============================================================
> ==================
> --- llvm/trunk/lib/CodeGen/LivePhysRegs.cpp (original)
> +++ llvm/trunk/lib/CodeGen/LivePhysRegs.cpp Fri Jan 26 12:23:00 2018
> @@ -225,10 +225,10 @@ void LivePhysRegs::addLiveOutsNoPristine
>
>  void LivePhysRegs::addLiveOuts(const MachineBasicBlock &MBB) {
>    const MachineFunction &MF = *MBB.getParent();
> -  if (!MBB.succ_empty()) {
> +  if (!MBB.isReturnBlock()) {
>      addPristines(MF);
>      addLiveOutsNoPristines(MBB);
> -  } else if (MBB.isReturnBlock()) {
> +  } else {
>      // For the return block: Add all callee saved registers.
>      const MachineFrameInfo &MFI = MF.getFrameInfo();
>      if (MFI.isCalleeSavedInfoValid())
>
> Added: llvm/trunk/test/CodeGen/Thumb/stm-scavenging.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/
> CodeGen/Thumb/stm-scavenging.ll?rev=323559&view=auto
> ============================================================
> ==================
> --- llvm/trunk/test/CodeGen/Thumb/stm-scavenging.ll (added)
> +++ llvm/trunk/test/CodeGen/Thumb/stm-scavenging.ll Fri Jan 26 12:23:00
> 2018
> @@ -0,0 +1,47 @@
> +; RUN: llc < %s | FileCheck %s
> +target triple = "thumbv6---gnueabi"
> +
> +; Use STM to save the three registers
> +; CHECK-LABEL: use_stm:
> +; CHECK: .save   {r7, lr}
> +; CHECK: .setfp  r7, sp
> +; CHECK: stm r3!, {r0, r1, r2}
> +; CHECK: bl throws_1
> +define void @use_stm(i32 %a, i32 %b, i32 %c, i32* %d) local_unnamed_addr
> noreturn "no-frame-pointer-elim"="true" {
> +entry:
> +  %arrayidx = getelementptr inbounds i32, i32* %d, i32 2
> +  store i32 %a, i32* %arrayidx, align 4
> +  %arrayidx1 = getelementptr inbounds i32, i32* %d, i32 3
> +  store i32 %b, i32* %arrayidx1, align 4
> +  %arrayidx2 = getelementptr inbounds i32, i32* %d, i32 4
> +  store i32 %c, i32* %arrayidx2, align 4
> +  tail call void @throws_1(i32 %a, i32 %b, i32 %c) noreturn
> +  unreachable
> +}
> +
> +; Don't use STM: there is no available register to store
> +; the address. We could transform this with some extra math, but
> +; that currently isn't implemented.
> +; CHECK-LABEL: no_stm:
> +; CHECK: .save   {r7, lr}
> +; CHECK: .setfp  r7, sp
> +; CHECK: str r0,
> +; CHECK: str r1,
> +; CHECK: str r2,
> +; CHECK: bl throws_2
> +define void @no_stm(i32 %a, i32 %b, i32 %c, i32* %d) local_unnamed_addr
> noreturn "no-frame-pointer-elim"="true" {
> +entry:
> +  %arrayidx = getelementptr inbounds i32, i32* %d, i32 2
> +  store i32 %a, i32* %arrayidx, align 4
> +  %arrayidx1 = getelementptr inbounds i32, i32* %d, i32 3
> +  store i32 %b, i32* %arrayidx1, align 4
> +  %arrayidx2 = getelementptr inbounds i32, i32* %d, i32 4
> +  store i32 %c, i32* %arrayidx2, align 4
> +  tail call void @throws_2(i32 %a, i32 %b, i32 %c, i32* %d) noreturn
> +  unreachable
> +}
> +
> +
> +declare void @throws_1(i32, i32, i32) noreturn
> +declare void @throws_2(i32, i32, i32, i32*) noreturn
> +
>
>
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