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[LegalizeDAG] Handle NeedInvert when expanding BR_CC 

This is a follow-up fix to commit 03c8d6a0c4.
Seems like we now end up with NeedInvert being set in the result
from LegalizeSetCCCondCode more often than in the past, so we
need to handle NeedInvert when expanding BR_CC.

Not sure how to deal with the "Tmp4.getNode()" case properly,
but current assumption is that that code path isn't impacted
by the changes in 03c8d6a0c4 so we can simply move
the old assert into the if-branch and only handle NeedInvert in the
else-branch.

I think that the test case added here, for PowerPC, might have
failed also before commit 03c8d6a0c4. But we started
to hit the assert more often downstream when having merged that
commit.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D94762
This commit is contained in:
Bjorn Pettersson 2021-01-15 10:35:56 +01:00
parent dbe056c2e3
commit 4f15556731
2 changed files with 36 additions and 3 deletions
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6
llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
View File

@ -3966,16 +3966,16 @@ bool SelectionDAGLegalize::ExpandNode(SDNode *Node) {
(void)Legalized;
assert(Legalized && "Can't legalize BR_CC with legal condition!");
assert(!NeedInvert && "Don't know how to invert BR_CC!");
// If we expanded the SETCC by swapping LHS and RHS, create a new BR_CC
// node.
if (Tmp4.getNode()) {
assert(!NeedInvert && "Don't know how to invert BR_CC!");
Tmp1 = DAG.getNode(ISD::BR_CC, dl, Node->getValueType(0), Tmp1,
Tmp4, Tmp2, Tmp3, Node->getOperand(4));
} else {
Tmp3 = DAG.getConstant(0, dl, Tmp2.getValueType());
Tmp4 = DAG.getCondCode(ISD::SETNE);
Tmp4 = DAG.getCondCode(NeedInvert ? ISD::SETEQ : ISD::SETNE);
Tmp1 = DAG.getNode(ISD::BR_CC, dl, Node->getValueType(0), Tmp1, Tmp4,
Tmp2, Tmp3, Node->getOperand(4));
}

33
llvm/test/CodeGen/PowerPC/legalize-invert-br_cc.ll Normal file
View File

@ -0,0 +1,33 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -O1 -mtriple powerpc -mattr=+spe -o - %s | FileCheck %s
; This used to hit an assert
;
; ../lib/CodeGen/SelectionDAG/LegalizeDAG.cpp:3971: bool {anonymous}::SelectionDAGLegalize::ExpandNode(llvm::SDNode*): Assertion `!NeedInvert && "Don't know how to invert BR_CC!"' failed.
define void @test_fcmpueq_legalize_br_cc_with_invert(float %a) {
; CHECK-LABEL: test_fcmpueq_legalize_br_cc_with_invert:
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: lis 4, .LCPI0_0@ha
; CHECK-NEXT: lwz 4, .LCPI0_0@l(4)
; CHECK-NEXT: .LBB0_1: # %l1
; CHECK-NEXT: #
; CHECK-NEXT: efscmplt 7, 3, 4
; CHECK-NEXT: efscmpgt 0, 3, 4
; CHECK-NEXT: mfcr 5 # cr7
; CHECK-NEXT: mcrf 7, 0
; CHECK-NEXT: mfcr 6 # cr7
; CHECK-NEXT: rlwinm 5, 5, 30, 31, 31
; CHECK-NEXT: rlwinm 6, 6, 30, 31, 31
; CHECK-NEXT: or. 5, 6, 5
; CHECK-NEXT: beq 0, .LBB0_1
; CHECK-NEXT: # %bb.2: # %l2
; CHECK-NEXT: blr
entry:
br label %l1
l1:
%fcmp = fcmp ueq float %a, 0xC6306B3440000000
br i1 %fcmp, label %l1, label %l2
l2:
ret void
}