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Revert "Allow X86::COND_NE_OR_P and X86::COND_NP_OR_E to be reversed."

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and "Add a missing test case for r258847."

This reverts commit r258847, r258848. Causes miscompilations and backend
errors.

llvm-svn: 258927
This commit is contained in:
Benjamin Kramer 2016-01-27 12:44:12 +00:00
parent 8817245f01
commit f14c1e99a1
7 changed files with 68 additions and 180 deletions
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94
lib/Target/X86/X86InstrInfo.cpp
View File

@ -3805,10 +3805,6 @@ X86::CondCode X86::GetOppositeBranchCondition(X86::CondCode CC) {
case X86::COND_NP: return X86::COND_P;
case X86::COND_O: return X86::COND_NO;
case X86::COND_NO: return X86::COND_O;
case X86::COND_NE_OR_P: return X86::COND_E_AND_NP;
case X86::COND_NP_OR_E: return X86::COND_P_AND_NE;
case X86::COND_E_AND_NP: return X86::COND_NE_OR_P;
case X86::COND_P_AND_NE: return X86::COND_NP_OR_E;
}
}
@ -4002,9 +3998,9 @@ bool X86InstrInfo::AnalyzeBranchImpl(
MachineBasicBlock::iterator OldInst = I;
BuildMI(MBB, UnCondBrIter, MBB.findDebugLoc(I), get(JNCC))
.addMBB(UnCondBrIter->getOperand(0).getMBB());
.addMBB(UnCondBrIter->getOperand(0).getMBB());
BuildMI(MBB, UnCondBrIter, MBB.findDebugLoc(I), get(X86::JMP_1))
.addMBB(TargetBB);
.addMBB(TargetBB);
OldInst->eraseFromParent();
UnCondBrIter->eraseFromParent();
@ -4028,6 +4024,11 @@ bool X86InstrInfo::AnalyzeBranchImpl(
assert(Cond.size() == 1);
assert(TBB);
// Only handle the case where all conditional branches branch to the same
// destination.
if (TBB != I->getOperand(0).getMBB())
return true;
// If the conditions are the same, we can leave them alone.
X86::CondCode OldBranchCode = (X86::CondCode)Cond[0].getImm();
if (OldBranchCode == BranchCode)
@ -4036,40 +4037,17 @@ bool X86InstrInfo::AnalyzeBranchImpl(
// If they differ, see if they fit one of the known patterns. Theoretically,
// we could handle more patterns here, but we shouldn't expect to see them
// if instruction selection has done a reasonable job.
auto NewTBB = I->getOperand(0).getMBB();
if (TBB == NewTBB &&
((OldBranchCode == X86::COND_NP && BranchCode == X86::COND_E) ||
(OldBranchCode == X86::COND_E && BranchCode == X86::COND_NP))) {
if ((OldBranchCode == X86::COND_NP &&
BranchCode == X86::COND_E) ||
(OldBranchCode == X86::COND_E &&
BranchCode == X86::COND_NP))
BranchCode = X86::COND_NP_OR_E;
} else if (TBB == NewTBB &&
((OldBranchCode == X86::COND_P && BranchCode == X86::COND_NE) ||
(OldBranchCode == X86::COND_NE && BranchCode == X86::COND_P))) {
else if ((OldBranchCode == X86::COND_P &&
BranchCode == X86::COND_NE) ||
(OldBranchCode == X86::COND_NE &&
BranchCode == X86::COND_P))
BranchCode = X86::COND_NE_OR_P;
} else if ((OldBranchCode == X86::COND_NE && BranchCode == X86::COND_NP) ||
(OldBranchCode == X86::COND_P && BranchCode == X86::COND_E)) {
// X86::COND_P_AND_NE usually has two different branch destinations.
//
// JNP B1
// JNE B2
// B1: (fall-through)
// B2:
//
// Here this condition branches to B2 only if P && NE. It has another
// equivalent form:
//
// JE B1
// JP B2
// B1: (fall-through)
// B2:
//
// Similarly it branches to B2 only if NE && P. That is why this condition
// is named COND_P_AND_NE.
BranchCode = X86::COND_P_AND_NE;
} else if ((OldBranchCode == X86::COND_NP && BranchCode == X86::COND_NE) ||
(OldBranchCode == X86::COND_E && BranchCode == X86::COND_P)) {
// See comments above for X86::COND_P_AND_NE.
BranchCode = X86::COND_E_AND_NP;
} else
else
return true;
// Update the MachineOperand.
@ -4178,13 +4156,6 @@ unsigned X86InstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
return Count;
}
static MachineBasicBlock *getFallThroughMBB(MachineBasicBlock *MBB) {
auto I = std::next(MBB->getIterator());
if (I == MBB->getParent()->end())
return nullptr;
return &*I;
}
unsigned
X86InstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
MachineBasicBlock *FBB, ArrayRef<MachineOperand> Cond,
@ -4201,9 +4172,6 @@ X86InstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
return 1;
}
// If FBB is null, it is implied to be a fall-through block.
bool FallThru = FBB == nullptr;
// Conditional branch.
unsigned Count = 0;
X86::CondCode CC = (X86::CondCode)Cond[0].getImm();
@ -4222,39 +4190,13 @@ X86InstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
BuildMI(&MBB, DL, get(X86::JP_1)).addMBB(TBB);
++Count;
break;
case X86::COND_P_AND_NE:
// Use the next block of MBB as FBB if it is null.
if (FBB == nullptr) {
FBB = getFallThroughMBB(&MBB);
assert(FBB && "MBB cannot be the last block in function when the false "
"body is a fall-through.");
}
// Synthesize NEG_NP_OR_E with two branches.
BuildMI(&MBB, DL, get(X86::JNP_1)).addMBB(FBB);
++Count;
BuildMI(&MBB, DL, get(X86::JNE_1)).addMBB(TBB);
++Count;
break;
case X86::COND_E_AND_NP:
// Use the next block of MBB as FBB if it is null.
if (FBB == nullptr) {
FBB = getFallThroughMBB(&MBB);
assert(FBB && "MBB cannot be the last block in function when the false "
"body is a fall-through.");
}
// Synthesize NEG_NE_OR_P with two branches.
BuildMI(&MBB, DL, get(X86::JNE_1)).addMBB(FBB);
++Count;
BuildMI(&MBB, DL, get(X86::JNP_1)).addMBB(TBB);
++Count;
break;
default: {
unsigned Opc = GetCondBranchFromCond(CC);
BuildMI(&MBB, DL, get(Opc)).addMBB(TBB);
++Count;
}
}
if (!FallThru) {
if (FBB) {
// Two-way Conditional branch. Insert the second branch.
BuildMI(&MBB, DL, get(X86::JMP_1)).addMBB(FBB);
++Count;
@ -6775,6 +6717,8 @@ bool X86InstrInfo::
ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
assert(Cond.size() == 1 && "Invalid X86 branch condition!");
X86::CondCode CC = static_cast<X86::CondCode>(Cond[0].getImm());
if (CC == X86::COND_NE_OR_P || CC == X86::COND_NP_OR_E)
return true;
Cond[0].setImm(GetOppositeBranchCondition(CC));
return false;
}

63
lib/Target/X86/X86InstrInfo.h
View File

@ -29,44 +29,35 @@ namespace llvm {
namespace X86 {
// X86 specific condition code. These correspond to X86_*_COND in
// X86InstrInfo.td. They must be kept in synch.
enum CondCode {
COND_A = 0,
COND_AE = 1,
COND_B = 2,
COND_BE = 3,
COND_E = 4,
COND_G = 5,
COND_GE = 6,
COND_L = 7,
COND_LE = 8,
COND_NE = 9,
COND_NO = 10,
COND_NP = 11,
COND_NS = 12,
COND_O = 13,
COND_P = 14,
COND_S = 15,
LAST_VALID_COND = COND_S,
enum CondCode {
COND_A = 0,
COND_AE = 1,
COND_B = 2,
COND_BE = 3,
COND_E = 4,
COND_G = 5,
COND_GE = 6,
COND_L = 7,
COND_LE = 8,
COND_NE = 9,
COND_NO = 10,
COND_NP = 11,
COND_NS = 12,
COND_O = 13,
COND_P = 14,
COND_S = 15,
LAST_VALID_COND = COND_S,
// Artificial condition codes. These are used by AnalyzeBranch
// to indicate a block terminated with two conditional branches to
// the same location. This occurs in code using FCMP_OEQ or FCMP_UNE,
// which can't be represented on x86 with a single condition. These
// are never used in MachineInstrs.
COND_NE_OR_P,
COND_NP_OR_E,
// Artificial condition codes. These are used by AnalyzeBranch
// to indicate a block terminated with two conditional branches to
// the same location. This occurs in code using FCMP_OEQ or FCMP_UNE,
// which can't be represented on x86 with a single condition. These
// are never used in MachineInstrs.
COND_NE_OR_P,
COND_NP_OR_E,
// Artificial condition codes. These are used to represent the negation of
// above two conditions. The only scenario we need these two conditions is
// when we try to reverse above two conditions in order to remove redundant
// unconditional jumps. Note that both true and false bodies need to be
// avaiable in order to correctly synthesize instructions for them. These are
// never used in MachineInstrs.
COND_E_AND_NP, // negate of COND_NE_OR_P
COND_P_AND_NE, // negate of COND_NP_OR_E
COND_INVALID
};
COND_INVALID
};
// Turn condition code into conditional branch opcode.
unsigned GetCondBranchFromCond(CondCode CC);

27
test/CodeGen/X86/block-placement.ll
View File

@ -463,23 +463,26 @@ exit:
}
define void @fpcmp_unanalyzable_branch(i1 %cond) {
; This function's CFG contains an once-unanalyzable branch (une on floating
; points). As now it becomes analyzable, we should get best layout in which each
; edge in 'entry' -> 'entry.if.then_crit_edge' -> 'if.then' -> 'if.end' is
; fall-through.
; This function's CFG contains an unanalyzable branch that is likely to be
; split due to having a different high-probability predecessor.
; CHECK: fpcmp_unanalyzable_branch
; CHECK: %entry
; CHECK: %entry.if.then_crit_edge
; CHECK: %if.then
; CHECK: %if.end
; CHECK: %exit
; CHECK-NOT: %if.then
; CHECK-NOT: %if.end
; CHECK-NOT: jne
; CHECK-NOT: jnp
; CHECK: jne
; CHECK-NEXT: jnp
; CHECK-NEXT: %if.then
entry:
; Note that this branch must be strongly biased toward
; 'entry.if.then_crit_edge' to ensure that we would try to form a chain for
; 'entry' -> 'entry.if.then_crit_edge' -> 'if.then' -> 'if.end'.
; 'entry' -> 'entry.if.then_crit_edge' -> 'if.then'. It is the last edge in that
; chain which would violate the unanalyzable branch in 'exit', but we won't even
; try this trick unless 'if.then' is believed to almost always be reached from
; 'entry.if.then_crit_edge'.
br i1 %cond, label %entry.if.then_crit_edge, label %lor.lhs.false, !prof !1
entry.if.then_crit_edge:
@ -491,7 +494,7 @@ lor.lhs.false:
exit:
%cmp.i = fcmp une double 0.000000e+00, undef
br i1 %cmp.i, label %if.then, label %if.end, !prof !3
br i1 %cmp.i, label %if.then, label %if.end
if.then:
%0 = phi i8 [ %.pre14, %entry.if.then_crit_edge ], [ undef, %exit ]
@ -504,7 +507,6 @@ if.end:
}
!1 = !{!"branch_weights", i32 1000, i32 1}
!3 = !{!"branch_weights", i32 1, i32 1000}
declare i32 @f()
declare i32 @g()
@ -663,14 +665,11 @@ define void @unanalyzable_branch_to_best_succ(i1 %cond) {
; Ensure that we can handle unanalyzable branches where the destination block
; gets selected as the optimal successor to merge.
;
; This branch is now analyzable and hence the destination block becomes the
; hotter one. The right order is entry->bar->exit->foo.
;
; CHECK: unanalyzable_branch_to_best_succ
; CHECK: %entry
; CHECK: %foo
; CHECK: %bar
; CHECK: %exit
; CHECK: %foo
entry:
; Bias this branch toward bar to ensure we form that chain.

5
test/CodeGen/X86/fast-isel-cmp-branch2.ll
View File

@ -5,7 +5,7 @@ define i32 @fcmp_oeq(float %x, float %y) {
; CHECK-LABEL: fcmp_oeq
; CHECK: ucomiss %xmm1, %xmm0
; CHECK-NEXT: jne {{LBB.+_1}}
; CHECK-NEXT: jp {{LBB.+_1}}
; CHECK-NEXT: jnp {{LBB.+_2}}
%1 = fcmp oeq float %x, %y
br i1 %1, label %bb1, label %bb2
bb2:
@ -162,7 +162,8 @@ define i32 @fcmp_une(float %x, float %y) {
; CHECK-LABEL: fcmp_une
; CHECK: ucomiss %xmm1, %xmm0
; CHECK-NEXT: jne {{LBB.+_2}}
; CHECK-NEXT: jnp {{LBB.+_1}}
; CHECK-NEXT: jp {{LBB.+_2}}
; CHECK-NEXT: jmp {{LBB.+_1}}
%1 = fcmp une float %x, %y
br i1 %1, label %bb1, label %bb2
bb2:

5
test/CodeGen/X86/fast-isel-cmp-branch3.ll
View File

@ -17,7 +17,7 @@ define i32 @fcmp_oeq2(float %x) {
; CHECK: xorps %xmm1, %xmm1
; CHECK-NEXT: ucomiss %xmm1, %xmm0
; CHECK-NEXT: jne {{LBB.+_1}}
; CHECK-NEXT: jp {{LBB.+_1}}
; CHECK-NEXT: jnp {{LBB.+_2}}
%1 = fcmp oeq float %x, 0.000000e+00
br i1 %1, label %bb1, label %bb2
bb2:
@ -338,7 +338,8 @@ define i32 @fcmp_une2(float %x) {
; CHECK: xorps %xmm1, %xmm1
; CHECK-NEXT: ucomiss %xmm1, %xmm0
; CHECK-NEXT: jne {{LBB.+_2}}
; CHECK-NEXT: jnp {{LBB.+_1}}
; CHECK-NEXT: jp {{LBB.+_2}}
; CHECK-NEXT: jmp {{LBB.+_1}}
%1 = fcmp une float %x, 0.000000e+00
br i1 %1, label %bb1, label %bb2
bb2:

33
test/CodeGen/X86/fp-une-cmp.ll
View File

@ -19,12 +19,12 @@
; addsd ...
; LBB0_2:
define float @func1(float %x, float %y) nounwind readnone optsize ssp {
; CHECK: func1
; CHECK: func
; CHECK: jne [[LABEL:.*]]
; CHECK-NEXT: jp [[LABEL]]
; CHECK-NOT: jmp
;
define float @func(float %x, float %y) nounwind readnone optsize ssp {
entry:
%0 = fpext float %x to double
%1 = fpext float %y to double
@ -41,30 +41,3 @@ bb2:
%.0 = fptrunc double %.0.in to float
ret float %.0
}
define float @func2(float %x, float %y) nounwind readnone optsize ssp {
; CHECK: func2
; CHECK: jne [[LABEL:.*]]
; CHECK-NEXT: jp [[LABEL]]
; CHECK: %bb2
; CHECK: %bb1
; CHECK: jmp
;
entry:
%0 = fpext float %x to double
%1 = fpext float %y to double
%2 = fmul double %0, %1
%3 = fcmp une double %2, 0.000000e+00
br i1 %3, label %bb1, label %bb2, !prof !1
bb1:
%4 = fadd double %2, -1.000000e+00
br label %bb2
bb2:
%.0.in = phi double [ %4, %bb1 ], [ %2, %entry ]
%.0 = fptrunc double %.0.in to float
ret float %.0
}
!1 = !{!"branch_weights", i32 1, i32 1000}

21
test/CodeGen/X86/x86-analyze-branch-jne-jp.ll
View File

@ -1,21 +0,0 @@
; RUN: llc -mcpu=corei7 -mtriple=x86_64-linux < %s | FileCheck %s -check-prefix=CHECK
; Test if the negation of the non-equality check between floating points are
; translated to jnp followed by jne.
; CHECK: jne
; CHECK-NEXT: jnp
define void @foo(float %f) {
entry:
%cmp = fcmp une float %f, 0.000000e+00
br i1 %cmp, label %if.then, label %if.end
if.then:
tail call void @a()
br label %if.end
if.end:
ret void
}
declare void @a()