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zmodemzmodem
committedFeb 23, 2018
Support for the mno-stack-arg-probe flag
Adds support for this flag. There is also another piece for clang (separate review). More info: https://bugs.llvm.org/show_bug.cgi?id=36221 By Ruslan Nikolaev! Differential Revision: https://reviews.llvm.org/D43107 llvm-svn: 325900
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‎llvm/docs/LangRef.rst

+2
Original file line numberDiff line numberDiff line change
@@ -1561,6 +1561,8 @@ example:
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inlined into a function that has no ``"stack-probe-size"`` attribute
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at all, the resulting function has the ``"stack-probe-size"`` attribute
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of the callee.
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``"no-stack-arg-probe"``
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This attribute disables ABI-required stack probes, if any.
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``writeonly``
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On a function, this attribute indicates that the function may write to but
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does not read from memory.

‎llvm/lib/Target/AArch64/AArch64FrameLowering.cpp

+2-1
Original file line numberDiff line numberDiff line change
@@ -369,7 +369,8 @@ static bool windowsRequiresStackProbe(MachineFunction &MF,
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F.getFnAttribute("stack-probe-size")
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.getValueAsString()
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.getAsInteger(0, StackProbeSize);
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return StackSizeInBytes >= StackProbeSize;
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return (StackSizeInBytes >= StackProbeSize) &&
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!F.hasFnAttribute("no-stack-arg-probe");
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}
374375

375376
bool AArch64FrameLowering::shouldCombineCSRLocalStackBump(

‎llvm/lib/Target/ARM/ARMFrameLowering.cpp

+2-1
Original file line numberDiff line numberDiff line change
@@ -209,7 +209,8 @@ static bool WindowsRequiresStackProbe(const MachineFunction &MF,
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F.getFnAttribute("stack-probe-size")
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.getValueAsString()
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.getAsInteger(0, StackProbeSize);
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return StackSizeInBytes >= StackProbeSize;
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return (StackSizeInBytes >= StackProbeSize) &&
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!F.hasFnAttribute("no-stack-arg-probe");
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}
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namespace {

‎llvm/lib/Target/X86/X86ISelLowering.cpp

+2-1
Original file line numberDiff line numberDiff line change
@@ -39186,7 +39186,8 @@ StringRef X86TargetLowering::getStackProbeSymbolName(MachineFunction &MF) const
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// Generally, if we aren't on Windows, the platform ABI does not include
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// support for stack probes, so don't emit them.
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if (!Subtarget.isOSWindows() || Subtarget.isTargetMachO())
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if (!Subtarget.isOSWindows() || Subtarget.isTargetMachO() ||
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MF.getFunction().hasFnAttribute("no-stack-arg-probe"))
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return "";
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// We need a stack probe to conform to the Windows ABI. Choose the right

‎llvm/lib/Target/X86/X86WinAllocaExpander.cpp

+19-7
Original file line numberDiff line numberDiff line change
@@ -62,6 +62,7 @@ class X86WinAllocaExpander : public MachineFunctionPass {
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unsigned StackPtr;
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unsigned SlotSize;
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int64_t StackProbeSize;
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bool NoStackArgProbe;
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StringRef getPassName() const override { return "X86 WinAlloca Expander"; }
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static char ID;
@@ -240,13 +241,21 @@ void X86WinAllocaExpander::lower(MachineInstr* MI, Lowering L) {
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}
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break;
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case Probe:
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// The probe lowering expects the amount in RAX/EAX.
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BuildMI(*MBB, MI, DL, TII->get(TargetOpcode::COPY), RegA)
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.addReg(MI->getOperand(0).getReg());
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// Do the probe.
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STI->getFrameLowering()->emitStackProbe(*MBB->getParent(), *MBB, MI, DL,
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/*InPrologue=*/false);
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if (!NoStackArgProbe) {
245+
// The probe lowering expects the amount in RAX/EAX.
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BuildMI(*MBB, MI, DL, TII->get(TargetOpcode::COPY), RegA)
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.addReg(MI->getOperand(0).getReg());
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// Do the probe.
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STI->getFrameLowering()->emitStackProbe(*MBB->getParent(), *MBB, MI, DL,
251+
/*InPrologue=*/false);
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} else {
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// Sub
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BuildMI(*MBB, I, DL, TII->get(Is64Bit ? X86::SUB64rr : X86::SUB32rr),
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StackPtr)
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.addReg(StackPtr)
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.addReg(MI->getOperand(0).getReg());
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}
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break;
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}
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@@ -285,6 +294,9 @@ bool X86WinAllocaExpander::runOnMachineFunction(MachineFunction &MF) {
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.getValueAsString()
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.getAsInteger(0, StackProbeSize);
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}
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NoStackArgProbe = MF.getFunction().hasFnAttribute("no-stack-arg-probe");
298+
if (NoStackArgProbe)
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StackProbeSize = INT64_MAX;
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LoweringMap Lowerings;
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computeLowerings(MF, Lowerings);

‎llvm/test/CodeGen/X86/no-stack-arg-probe.ll

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,38 @@
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; This test is attempting to detect that the compiler disables stack
2+
; probe calls when the corresponding option is specified.
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;
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; RUN: llc -mtriple=i686-windows-msvc < %s | FileCheck %s
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target datalayout = "e-m:w-p:32:32-i64:64-f80:32-n8:16:32-S32"
7+
8+
define i32 @test1() "no-stack-arg-probe" {
9+
%buffer = alloca [4095 x i8]
10+
11+
ret i32 0
12+
13+
; CHECK-LABEL: _test1:
14+
; CHECK-NOT: movl $4095, %eax
15+
; CHECK: subl $4095, %esp
16+
; CHECK-NOT: calll __chkstk
17+
}
18+
19+
define i32 @test2() "no-stack-arg-probe" {
20+
%buffer = alloca [4096 x i8]
21+
22+
ret i32 0
23+
24+
; CHECK-LABEL: _test2:
25+
; CHECK-NOT: movl $4096, %eax
26+
; CHECK: subl $4096, %esp
27+
; CHECK-NOT: calll __chkstk
28+
}
29+
30+
define i32 @test3(i32 %size) "no-stack-arg-probe" {
31+
%buffer = alloca i8, i32 %size
32+
33+
ret i32 0
34+
35+
; CHECK-LABEL: _test3:
36+
; CHECK: subl {{.*}}, %esp
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; CHECK-NOT: calll __chkstk
38+
}

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