From 2e8ee4b459a0f5931e6e5632a449be0ef971e070 Mon Sep 17 00:00:00 2001 From: Stanislav Mekhanoshin Date: Fri, 20 Sep 2019 15:26:10 +0000 Subject: [PATCH] Remove assert from MachineLoop::getLoopPredecessor() According to the documentation method returns predecessor if the given loop's header has exactly one unique predecessor outside the loop. Otherwise return null. In reality it asserts if there is no predecessor outside of the loop. The testcase has the loop where predecessors outside of the loop were not identified as analyzeBranch() was unable to process the mask branch and returned true. That is also not correct to assert for the truly dead loops. Differential Revision: https://reviews.llvm.org/D67634 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@372405 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Analysis/LoopInfoImpl.h | 2 - test/CodeGen/AMDGPU/loop_header_nopred.mir | 92 ++++++++++++++++++++++ 2 files changed, 92 insertions(+), 2 deletions(-) create mode 100644 test/CodeGen/AMDGPU/loop_header_nopred.mir diff --git a/include/llvm/Analysis/LoopInfoImpl.h b/include/llvm/Analysis/LoopInfoImpl.h index 4c33dac9e21..2f38dde7b3a 100644 --- a/include/llvm/Analysis/LoopInfoImpl.h +++ b/include/llvm/Analysis/LoopInfoImpl.h @@ -200,8 +200,6 @@ BlockT *LoopBase::getLoopPredecessor() const { } } - // Make sure there is only one exit out of the preheader. - assert(Out && "Header of loop has no predecessors from outside loop?"); return Out; } diff --git a/test/CodeGen/AMDGPU/loop_header_nopred.mir b/test/CodeGen/AMDGPU/loop_header_nopred.mir new file mode 100644 index 00000000000..a1f23777e30 --- /dev/null +++ b/test/CodeGen/AMDGPU/loop_header_nopred.mir @@ -0,0 +1,92 @@ +# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py +# RUN: llc -march=amdgcn -o - -run-pass=block-placement -mcpu=gfx1010 -mattr=-inst-fwd-prefetch-bug -verify-machineinstrs %s | FileCheck -check-prefix=GCN %s + +# Used to fail with +# Assertion `Out && "Header of loop has no predecessors from outside loop?" + +--- +name: loop_header_nopred +body: | + ; GCN-LABEL: name: loop_header_nopred + ; GCN: bb.0: + ; GCN: successors: %bb.2(0x40000000), %bb.3(0x40000000) + ; GCN: S_CBRANCH_VCCZ %bb.3, implicit $vcc + ; GCN: S_BRANCH %bb.2 + ; GCN: bb.6 (align 64): + ; GCN: successors: %bb.7(0x04000000), %bb.1(0x7c000000) + ; GCN: S_CBRANCH_VCCNZ %bb.7, implicit $vcc + ; GCN: bb.1: + ; GCN: successors: %bb.2(0x40000000), %bb.3(0x40000000) + ; GCN: S_CBRANCH_VCCNZ %bb.2, implicit $vcc + ; GCN: bb.3: + ; GCN: successors: %bb.4(0x40000000), %bb.6(0x40000000) + ; GCN: SI_MASK_BRANCH %bb.6, implicit $exec + ; GCN: S_BRANCH %bb.4 + ; GCN: bb.2 (align 64): + ; GCN: successors: %bb.4(0x40000000), %bb.6(0x40000000) + ; GCN: SI_MASK_BRANCH %bb.6, implicit $exec + ; GCN: S_BRANCH %bb.4 + ; GCN: bb.4: + ; GCN: successors: %bb.5(0x04000000), %bb.4(0x7c000000) + ; GCN: S_NOP 0 + ; GCN: S_NOP 0 + ; GCN: S_NOP 0 + ; GCN: S_NOP 0 + ; GCN: S_NOP 0 + ; GCN: S_NOP 0 + ; GCN: S_NOP 0 + ; GCN: S_NOP 0 + ; GCN: S_NOP 0 + ; GCN: S_NOP 0 + ; GCN: S_NOP 0 + ; GCN: S_CBRANCH_EXECZ %bb.4, implicit $exec + ; GCN: bb.5: + ; GCN: successors: %bb.6(0x80000000) + ; GCN: S_BRANCH %bb.6 + ; GCN: bb.7: + ; GCN: S_ENDPGM 0 + bb.0: + successors: %bb.1(0x80000000) + + bb.1: + successors: %bb.2(0x40000000), %bb.3(0x40000000) + + S_CBRANCH_VCCZ %bb.3, implicit $vcc + S_BRANCH %bb.2 + + bb.2: + successors: %bb.3(0x80000000) + + bb.3: + successors: %bb.4(0x40000000), %bb.6(0x40000000) + + SI_MASK_BRANCH %bb.6, implicit $exec + S_BRANCH %bb.4 + + bb.4: + successors: %bb.5(0x04000000), %bb.4(0x7c000000) + + S_NOP 0 + S_NOP 0 + S_NOP 0 + S_NOP 0 + S_NOP 0 + S_NOP 0 + S_NOP 0 + S_NOP 0 + S_NOP 0 + S_NOP 0 + S_NOP 0 + S_CBRANCH_EXECZ %bb.4, implicit $exec + + bb.5: + successors: %bb.6(0x80000000) + + bb.6: + successors: %bb.7(0x04000000), %bb.1(0x7c000000) + + S_CBRANCH_VCCZ %bb.1, implicit $vcc + + bb.7: + S_ENDPGM 0 +... -- 2.40.0