From 62632b78b011109063d39707bed2c1b6aac01f6f Mon Sep 17 00:00:00 2001 From: Eli Friedman Date: Mon, 9 Sep 2019 18:29:27 +0000 Subject: [PATCH] [IfConversion] Correctly handle cases where analyzeBranch fails. If analyzeBranch fails, on some targets, the out parameters point to some blocks in the function. But we can't use that information, so make sure to clear it out. (In some places in IfConversion, we assume that any block with a TrueBB is analyzable.) The change to the testcase makes it trigger a bug on builds without this fix: IfConvertDiamond tries to perform a followup "merge" operation, which isn't legal, and we somehow end up with a branch to a deleted MBB. I'm not sure how this doesn't crash the compiler. Differential Revision: https://reviews.llvm.org/D67306 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@371434 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/IfConversion.cpp | 6 ++++++ test/CodeGen/ARM/ifcvt-diamond-unanalyzable-common.mir | 5 ++--- 2 files changed, 8 insertions(+), 3 deletions(-) diff --git a/lib/CodeGen/IfConversion.cpp b/lib/CodeGen/IfConversion.cpp index be30ad30016..99f59f2f946 100644 --- a/lib/CodeGen/IfConversion.cpp +++ b/lib/CodeGen/IfConversion.cpp @@ -912,6 +912,12 @@ void IfConverter::AnalyzeBranches(BBInfo &BBI) { BBI.BrCond.clear(); BBI.IsBrAnalyzable = !TII->analyzeBranch(*BBI.BB, BBI.TrueBB, BBI.FalseBB, BBI.BrCond); + if (!BBI.IsBrAnalyzable) { + BBI.TrueBB = nullptr; + BBI.FalseBB = nullptr; + BBI.BrCond.clear(); + } + SmallVector RevCond(BBI.BrCond.begin(), BBI.BrCond.end()); BBI.IsBrReversible = (RevCond.size() == 0) || !TII->reverseBranchCondition(RevCond); diff --git a/test/CodeGen/ARM/ifcvt-diamond-unanalyzable-common.mir b/test/CodeGen/ARM/ifcvt-diamond-unanalyzable-common.mir index 57636218403..a2218b149f1 100644 --- a/test/CodeGen/ARM/ifcvt-diamond-unanalyzable-common.mir +++ b/test/CodeGen/ARM/ifcvt-diamond-unanalyzable-common.mir @@ -1,4 +1,4 @@ -# RUN: llc %s -o - -run-pass=if-converter | FileCheck %s +# RUN: llc %s -o - -run-pass=if-converter -verify-machineinstrs | FileCheck %s # Make sure we correctly if-convert blocks containing an INLINEASM_BR. # CHECK: t2CMPri killed renamable $r2, 34 # CHECK-NEXT: $r0 = t2MOVi 2, 1, $cpsr, $noreg @@ -48,9 +48,8 @@ body: | t2B %bb.3, 14, $noreg bb.3: - successors: %bb.4(0x80000000) - INLINEASM &"", 1 + $sp = t2LDMIA_RET $sp, 14, $noreg, def $r4, def $pc bb.4.l_yes (address-taken): $sp = t2LDMIA_RET $sp, 14, $noreg, def $r4, def $pc -- 2.50.1