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Revert "Allow output constraints on "asm goto"" 

This reverts commit 52366088a8.

I accidentally pushed this before supporting changes.
This commit is contained in:
Bill Wendling 2020-01-07 13:43:04 -08:00
parent 06d122bc42
commit e886e762dd
9 changed files with 39 additions and 243 deletions
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32
llvm/docs/LangRef.rst
View File

@ -7099,14 +7099,14 @@ Syntax:
::
<result> = callbr [cconv] [ret attrs] [addrspace(<num>)] <ty>|<fnty> <fnptrval>(<function args>) [fn attrs]
[operand bundles] to label <fallthrough label> [indirect labels]
[operand bundles] to label <normal label> [other labels]
Overview:
"""""""""
The '``callbr``' instruction causes control to transfer to a specified
function, with the possibility of control flow transfer to either the
'``fallthrough``' label or one of the '``indirect``' labels.
'``normal``' label or one of the '``other``' labels.
This instruction should only be used to implement the "goto" feature of gcc
style inline assembly. Any other usage is an error in the IR verifier.
@ -7133,17 +7133,17 @@ This instruction requires several arguments:
type can be omitted if the function is not varargs.
#. '``fnptrval``': An LLVM value containing a pointer to a function to
be called. In most cases, this is a direct function call, but
other ``callbr``'s are just as possible, calling an arbitrary pointer
indirect ``callbr``'s are just as possible, calling an arbitrary pointer
to function value.
#. '``function args``': argument list whose types match the function
signature argument types and parameter attributes. All arguments must
be of :ref:`first class <t_firstclass>` type. If the function signature
indicates the function accepts a variable number of arguments, the
extra arguments can be specified.
#. '``fallthrough label``': the label reached when the inline assembly's
execution exits the bottom.
#. '``indirect labels``': the labels reached when a callee transfers control
to a location other than the '``fallthrough label``'. The blockaddress
#. '``normal label``': the label reached when the called function
executes a '``ret``' instruction.
#. '``other labels``': the labels reached when a callee transfers control
to a location other than the normal '``normal label``'. The blockaddress
constant for these should also be in the list of '``function args``'.
#. The optional :ref:`function attributes <fnattrs>` list.
#. The optional :ref:`operand bundles <opbundles>` list.
@ -7156,13 +7156,6 @@ instruction in most regards. The primary difference is that it
establishes an association with additional labels to define where control
flow goes after the call.
Outputs of a '``callbr``' instruction are valid only on the '``fallthrough``'
path. Use of outputs on the '``indirect``' path(s) results in :ref:`poison
values <poisonvalues>`. Care should be taken if the '``fallthrough``' block is
also listed in the '``indirect``' blocks. The outputs may or may not result in
:ref:`poison values <poisonvalues>` depending on the behavior of the inline
assembly.
The only use of this today is to implement the "goto" feature of gcc inline
assembly where additional labels can be provided as locations for the inline
assembly to jump to.
@ -7170,15 +7163,10 @@ assembly to jump to.
Example:
""""""""
.. code-block:: llvm
.. code-block:: text
; "asm goto" without output constraints.
callbr void asm "", "r,X"(i32 %x, i8 *blockaddress(@foo, %indirect))
to label %fallthrough [label %indirect]
; "asm goto" with output constraints.
<result> = callbr i32 asm "", "=r,r,X"(i32 %x, i8 *blockaddress(@foo, %indirect))
to label %fallthrough [label %indirect]
callbr void asm "", "r,x"(i32 %x, i8 *blockaddress(@foo, %fail))
to label %normal [label %fail]
.. _i_resume:

9
llvm/include/llvm/CodeGen/MachineBasicBlock.h
View File

@ -129,9 +129,6 @@ private:
/// Indicate that this basic block is the entry block of a cleanup funclet.
bool IsCleanupFuncletEntry = false;
/// Indicate that this basic block is the indirect dest of an INLINEASM_BR.
bool IsInlineAsmBrIndirectPad = false;
/// since getSymbol is a relatively heavy-weight operation, the symbol
/// is only computed once and is cached.
mutable MCSymbol *CachedMCSymbol = nullptr;
@ -411,12 +408,6 @@ public:
/// Indicates if this is the entry block of a cleanup funclet.
void setIsCleanupFuncletEntry(bool V = true) { IsCleanupFuncletEntry = V; }
/// Returns true if this is the indirect dest of an INLINEASM_BR.
bool isInlineAsmBrIndirectPad() const { return IsInlineAsmBrIndirectPad; }
/// Indicates if this is the indirect dest of an INLINEASM_BR.
void setIsInlineAsmBrIndirectPad(bool V = true) { IsInlineAsmBrIndirectPad = V; }
/// Returns true if it is legal to hoist instructions into this block.
bool isLegalToHoistInto() const;

3
llvm/lib/AsmParser/LLParser.cpp
View File

@ -6419,6 +6419,9 @@ bool LLParser::ParseCallBr(Instruction *&Inst, PerFunctionState &PFS) {
/*IsCall=*/true))
return true;
if (isa<InlineAsm>(Callee) && !Ty->getReturnType()->isVoidTy())
return Error(RetTypeLoc, "asm-goto outputs not supported");
// Set up the Attribute for the function.
SmallVector<Value *, 8> Args;
SmallVector<AttributeSet, 8> ArgAttrs;

11
llvm/lib/CodeGen/MachineBasicBlock.cpp
View File

@ -1109,17 +1109,6 @@ bool MachineBasicBlock::canSplitCriticalEdge(
if (Succ->isEHPad())
return false;
// Splitting the critical edge to a callbr's indirect block isn't advised.
// Don't do it in this generic function.
if (Succ->hasAddressTaken())
if (auto *cbr = dyn_cast<CallBrInst>(getBasicBlock()->getTerminator()))
if (auto *bb = Succ->getBasicBlock())
if (cbr->getDefaultDest() != bb)
if (llvm::any_of(cbr->getIndirectDests(), [&](const BasicBlock *succ){
return succ == bb;
}))
return false;
const MachineFunction *MF = getParent();
// Performance might be harmed on HW that implements branching using exec mask

50
llvm/lib/CodeGen/MachineVerifier.cpp
View File

@ -633,30 +633,17 @@ MachineVerifier::visitMachineBasicBlockBefore(const MachineBasicBlock *MBB) {
}
// Count the number of landing pad successors.
SmallPtrSet<const MachineBasicBlock*, 4> LandingPadSuccs;
for (const auto *succ : MBB->successors()) {
if (succ->isEHPad())
LandingPadSuccs.insert(succ);
if (!FunctionBlocks.count(succ))
SmallPtrSet<MachineBasicBlock*, 4> LandingPadSuccs;
for (MachineBasicBlock::const_succ_iterator I = MBB->succ_begin(),
E = MBB->succ_end(); I != E; ++I) {
if ((*I)->isEHPad())
LandingPadSuccs.insert(*I);
if (!FunctionBlocks.count(*I))
report("MBB has successor that isn't part of the function.", MBB);
if (!MBBInfoMap[succ].Preds.count(MBB)) {
if (!MBBInfoMap[*I].Preds.count(MBB)) {
report("Inconsistent CFG", MBB);
errs() << "MBB is not in the predecessor list of the successor "
<< printMBBReference(*succ) << ".\n";
}
}
// Count the number of INLINEASM_BR indirect pad successors.
SmallPtrSet<const MachineBasicBlock*, 4> IndirectPadSuccs;
for (const auto *succ : MBB->successors()) {
if (succ->isInlineAsmBrIndirectPad())
IndirectPadSuccs.insert(succ);
if (!FunctionBlocks.count(succ))
report("MBB has successor that isn't part of the function.", MBB);
if (!MBBInfoMap[succ].Preds.count(MBB)) {
report("Inconsistent CFG", MBB);
errs() << "MBB is not in the predecessor list of the successor "
<< printMBBReference(*succ) << ".\n";
<< printMBBReference(*(*I)) << ".\n";
}
}
@ -697,13 +684,11 @@ MachineVerifier::visitMachineBasicBlockBefore(const MachineBasicBlock *MBB) {
// It's possible that the block legitimately ends with a noreturn
// call or an unreachable, in which case it won't actually fall
// out the bottom of the function.
} else if (MBB->succ_size() == LandingPadSuccs.size() ||
MBB->succ_size() == IndirectPadSuccs.size()) {
} else if (MBB->succ_size() == LandingPadSuccs.size()) {
// It's possible that the block legitimately ends with a noreturn
// call or an unreachable, in which case it won't actually fall
// out of the block.
} else if (MBB->succ_size() != 1 + LandingPadSuccs.size() &&
MBB->succ_size() != 1 + IndirectPadSuccs.size()) {
} else if (MBB->succ_size() != 1+LandingPadSuccs.size()) {
report("MBB exits via unconditional fall-through but doesn't have "
"exactly one CFG successor!", MBB);
} else if (!MBB->isSuccessor(&*MBBI)) {
@ -725,10 +710,7 @@ MachineVerifier::visitMachineBasicBlockBefore(const MachineBasicBlock *MBB) {
// landingpad, accept it as valid control flow.
if (MBB->succ_size() != 1+LandingPadSuccs.size() &&
(MBB->succ_size() != 1 || LandingPadSuccs.size() != 1 ||
*MBB->succ_begin() != *LandingPadSuccs.begin()) &&
MBB->succ_size() != 1 + IndirectPadSuccs.size() &&
(MBB->succ_size() != 1 || IndirectPadSuccs.size() != 1 ||
*MBB->succ_begin() != *IndirectPadSuccs.begin())) {
*MBB->succ_begin() != *LandingPadSuccs.begin())) {
report("MBB exits via unconditional branch but doesn't have "
"exactly one CFG successor!", MBB);
} else if (!MBB->isSuccessor(TBB)) {
@ -858,14 +840,8 @@ void MachineVerifier::visitMachineBundleBefore(const MachineInstr *MI) {
if (!FirstTerminator)
FirstTerminator = MI;
} else if (FirstTerminator && !MI->isDebugEntryValue()) {
// An "INLINEASM_BR" will fallthrough to the successor block executing any
// "COPY" instructions that exist so that they can be assigned in the
// fallthrough block..
if (FirstTerminator->getOpcode() != TargetOpcode::INLINEASM_BR ||
MI->getOpcode() != TargetOpcode::COPY) {
report("Non-terminator instruction after the first terminator", MI);
errs() << "First terminator was:\t" << *FirstTerminator;
}
report("Non-terminator instruction after the first terminator", MI);
errs() << "First terminator was:\t" << *FirstTerminator;
}
}

2
llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
View File

@ -2847,7 +2847,6 @@ void SelectionDAGBuilder::visitCallBr(const CallBrInst &I) {
assert(isa<InlineAsm>(I.getCalledValue()) &&
"Only know how to handle inlineasm callbr");
visitInlineAsm(&I);
CopyToExportRegsIfNeeded(&I);
// Retrieve successors.
MachineBasicBlock *Return = FuncInfo.MBBMap[I.getDefaultDest()];
@ -2857,7 +2856,6 @@ void SelectionDAGBuilder::visitCallBr(const CallBrInst &I) {
for (unsigned i = 0, e = I.getNumIndirectDests(); i < e; ++i) {
MachineBasicBlock *Target = FuncInfo.MBBMap[I.getIndirectDest(i)];
addSuccessorWithProb(CallBrMBB, Target);
Target->setIsInlineAsmBrIndirectPad();
}
CallBrMBB->normalizeSuccProbs();

2
llvm/lib/IR/Verifier.cpp
View File

@ -2501,6 +2501,8 @@ void Verifier::visitIndirectBrInst(IndirectBrInst &BI) {
void Verifier::visitCallBrInst(CallBrInst &CBI) {
Assert(CBI.isInlineAsm(), "Callbr is currently only used for asm-goto!",
&CBI);
Assert(CBI.getType()->isVoidTy(), "Callbr return value is not supported!",
&CBI);
for (unsigned i = 0, e = CBI.getNumSuccessors(); i != e; ++i)
Assert(CBI.getSuccessor(i)->getType()->isLabelTy(),
"Callbr successors must all have pointer type!", &CBI);

120
llvm/test/CodeGen/X86/callbr-asm-outputs.ll
View File

@ -1,118 +1,18 @@
; RUN: llc -mtriple=i686-- -verify-machineinstrs < %s | FileCheck %s
; RUN: not llc -mtriple=i686-- < %s 2> %t
; RUN: FileCheck %s < %t
; A test for asm-goto output
; CHECK: error: asm-goto outputs not supported
; CHECK-LABEL: test1:
; CHECK: movl 4(%esp), %eax
; CHECK-NEXT: addl $4, %eax
; CHECK-NEXT: #APP
; CHECK-NEXT: xorl %eax, %eax
; CHECK-NEXT: jmp .Ltmp0
; CHECK-NEXT: #NO_APP
; CHECK-NEXT: .LBB0_1:
; CHECK-NEXT: retl
; CHECK-NEXT: .Ltmp0:
define i32 @test1(i32 %x) {
; A test for asm-goto output prohibition
define i32 @test(i32 %a) {
entry:
%add = add nsw i32 %x, 4
%ret = callbr i32 asm "xorl $1, $0; jmp ${2:l}", "=r,r,X,~{dirflag},~{fpsr},~{flags}"(i32 %add, i8* blockaddress(@test1, %abnormal))
to label %normal [label %abnormal]
%0 = add i32 %a, 4
%1 = callbr i32 asm "xorl $1, $1; jmp ${1:l}", "=&r,r,X,~{dirflag},~{fpsr},~{flags}"(i32 %0, i8* blockaddress(@test, %fail)) to label %normal [label %fail]
normal:
ret i32 %ret
ret i32 %1
abnormal:
fail:
ret i32 1
}
; CHECK-LABEL: test2:
; CHECK: # %bb.1: # %if.then
; CHECK-NEXT: #APP
; CHECK-NEXT: testl %esi, %esi
; CHECK-NEXT: testl %edi, %esi
; CHECK-NEXT: jne .Ltmp1
; CHECK-NEXT: #NO_APP
; CHECK-NEXT: .LBB1_2:
; CHECK-NEXT: jmp .LBB1_4
; CHECK-NEXT: .LBB1_3: # %if.else
; CHECK-NEXT: #APP
; CHECK-NEXT: testl %esi, %edi
; CHECK-NEXT: testl %esi, %edi
; CHECK-NEXT: jne .Ltmp2
; CHECK-NEXT: #NO_APP
; CHECK-NEXT: .LBB1_4:
; CHECK-NEXT: movl %esi, %eax
; CHECK-NEXT: addl %edi, %eax
; CHECK-NEXT: jmp .LBB1_6
; CHECK-NEXT: .Ltmp1:
; CHECK-NEXT: .LBB1_5: # %label_true
; CHECK-NEXT: movl $-2, %eax
; CHECK-NEXT: .Ltmp2:
; CHECK-NEXT: .LBB1_6: # %return
define i32 @test2(i32 %out1, i32 %out2) {
entry:
%cmp = icmp slt i32 %out1, %out2
br i1 %cmp, label %if.then, label %if.else
if.then: ; preds = %entry
%0 = callbr { i32, i32 } asm sideeffect "testl $0, $0; testl $1, $2; jne ${5:l}", "={si},={di},r,0,1,X,X,~{dirflag},~{fpsr},~{flags}"(i32 %out1, i32 %out1, i32 %out2, i8* blockaddress(@test2, %label_true), i8* blockaddress(@test2, %return))
to label %if.end [label %label_true, label %return]
if.else: ; preds = %entry
%1 = callbr { i32, i32 } asm sideeffect "testl $0, $1; testl $2, $3; jne ${7:l}", "={si},={di},r,r,0,1,X,X,~{dirflag},~{fpsr},~{flags}"(i32 %out1, i32 %out2, i32 %out1, i32 %out2, i8* blockaddress(@test2, %label_true), i8* blockaddress(@test2, %return))
to label %if.end [label %label_true, label %return]
if.end: ; preds = %if.else, %if.then
%.sink11 = phi { i32, i32 } [ %0, %if.then ], [ %1, %if.else ]
%asmresult3 = extractvalue { i32, i32 } %.sink11, 0
%asmresult4 = extractvalue { i32, i32 } %.sink11, 1
%add = add nsw i32 %asmresult4, %asmresult3
br label %return
label_true: ; preds = %if.else, %if.then
br label %return
return: ; preds = %if.then, %if.else, %label_true, %if.end
%retval.0 = phi i32 [ %add, %if.end ], [ -2, %label_true ], [ -1, %if.else ], [ -1, %if.then ]
ret i32 %retval.0
}
; CHECK-LABEL: test3:
; CHECK: # %bb.1: # %true
; CHECK-NEXT: #APP
; CHECK-NEXT: .short %esi
; CHECK-NEXT: .short %edi
; CHECK-NEXT: #NO_APP
; CHECK-NEXT: .LBB2_2:
; CHECK-NEXT: movl %edi, %eax
; CHECK-NEXT: jmp .LBB2_5
; CHECK-NEXT: .LBB2_3: # %false
; CHECK-NEXT: #APP
; CHECK-NEXT: .short %eax
; CHECK-NEXT: .short %edx
; CHECK-NEXT: #NO_APP
; CHECK-NEXT: .LBB2_4:
; CHECK-NEXT: movl %edx, %eax
; CHECK-NEXT: jmp .LBB2_5
; CHECK-NEXT: .Ltmp3: # Block address taken
; CHECK-NEXT: .LBB2_6: # %indirect
; CHECK-NEXT: movl $42, %eax
; CHECK-NEXT: .LBB2_5: # %asm.fallthrough
define i32 @test3(i1 %cmp) {
entry:
br i1 %cmp, label %true, label %false
true:
%0 = callbr { i32, i32 } asm sideeffect ".word $0, $1", "={si},={di},X" (i8* blockaddress(@test3, %indirect)) to label %asm.fallthrough [label %indirect]
false:
%1 = callbr { i32, i32 } asm sideeffect ".word $0, $1", "={ax},={dx},X" (i8* blockaddress(@test3, %indirect)) to label %asm.fallthrough [label %indirect]
asm.fallthrough:
%vals = phi { i32, i32 } [ %0, %true ], [ %1, %false ]
%v = extractvalue { i32, i32 } %vals, 1
ret i32 %v
indirect:
ret i32 42
}

53
llvm/test/CodeGen/X86/callbr-asm.ll
View File

@ -1,5 +1,5 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=i686-- -O3 -verify-machineinstrs | FileCheck %s
; RUN: llc < %s -mtriple=i686-- -O3 | FileCheck %s
; Tests for using callbr as an asm-goto wrapper
@ -159,54 +159,3 @@ quux: ; preds = %asm.fallthrough, %e
cleanup: ; preds = %asm.fallthrough, %quux
ret void
}
define i32 @test5(i32 %out1, i32 %out2) {
; Test 5 - asm-goto with output constraints.
; CHECK-LABEL: test5:
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: movl $-1, %eax
; CHECK-NEXT: movl 4(%esp), %ecx
; CHECK-NEXT: #APP
; CHECK-NEXT: testl %ecx, %ecx
; CHECK-NEXT: testl %edx, %ecx
; CHECK-NEXT: jne .Ltmp6
; CHECK-NEXT: #NO_APP
; CHECK-NEXT: .LBB4_1:
; CHECK-NEXT: #APP
; CHECK-NEXT: testl %ecx, %edx
; CHECK-NEXT: testl %ecx, %edx
; CHECK-NEXT: jne .Ltmp7
; CHECK-NEXT: #NO_APP
; CHECK-NEXT: .LBB4_2:
; CHECK-NEXT: addl %edx, %ecx
; CHECK-NEXT: movl %ecx, %eax
; CHECK-NEXT: retl
; CHECK-NEXT: .Ltmp6:
; CHECK-NEXT: .LBB4_3:
; CHECK-NEXT: movl $-2, %eax
; CHECK-NEXT: .Ltmp7:
; CHECK-NEXT: .LBB4_4:
; CHECK-NEXT: retl
entry:
%0 = callbr { i32, i32 } asm sideeffect "testl $0, $0; testl $1, $2; jne ${3:l}", "=r,=r,r,X,X,~{dirflag},~{fpsr},~{flags}"(i32 %out1, i8* blockaddress(@test5, %label_true), i8* blockaddress(@test5, %return))
to label %asm.fallthrough [label %label_true, label %return]
asm.fallthrough: ; preds = %entry
%asmresult = extractvalue { i32, i32 } %0, 0
%asmresult1 = extractvalue { i32, i32 } %0, 1
%1 = callbr { i32, i32 } asm sideeffect "testl $0, $1; testl $2, $3; jne ${5:l}", "=r,=r,r,r,X,X,~{dirflag},~{fpsr},~{flags}"(i32 %asmresult, i32 %asmresult1, i8* blockaddress(@test5, %label_true), i8* blockaddress(@test5, %return))
to label %asm.fallthrough2 [label %label_true, label %return]
asm.fallthrough2: ; preds = %asm.fallthrough
%asmresult3 = extractvalue { i32, i32 } %1, 0
%asmresult4 = extractvalue { i32, i32 } %1, 1
%add = add nsw i32 %asmresult3, %asmresult4
br label %return
label_true: ; preds = %asm.fallthrough, %entry
br label %return
return: ; preds = %entry, %asm.fallthrough, %label_true, %asm.fallthrough2
%retval.0 = phi i32 [ %add, %asm.fallthrough2 ], [ -2, %label_true ], [ -1, %asm.fallthrough ], [ -1, %entry ]
ret i32 %retval.0
}