[MIR] Skip hoisting to basic block which may throw exception or return

Summary:
Fix hoisting to basic block which are not legal for hoisting cause
it can be terminated by exception or it is return block.

Reviewers: john.brawn, RKSimon, MatzeB

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63148

llvm-svn: 363164

2 files changed, 54 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/MachineCSE.cpp b/llvm/lib/CodeGen/MachineCSE.cpp
index d05e7f542d0..2df6d40d929 100644
--- a/llvm/lib/CodeGen/MachineCSE.cpp
+++ b/llvm/lib/CodeGen/MachineCSE.cpp
@@ -799,6 +799,8 @@ bool MachineCSE::ProcessBlockPRE(MachineDominatorTree *DT,
         !DT->properlyDominates(MBB, MBB1) &&
         "MBB cannot properly dominate MBB1 while DFS through dominators tree!");
     auto CMBB = DT->findNearestCommonDominator(MBB, MBB1);
+    if (!CMBB->isLegalToHoistInto())
+      continue;
 
     // Two instrs are partial redundant if their basic blocks are reachable
     // from one to another but one doesn't dominate another.
diff --git a/llvm/test/CodeGen/AArch64/machine_cse_illegal_hoist.ll b/llvm/test/CodeGen/AArch64/machine_cse_illegal_hoist.ll
new file mode 100644
index 00000000000..a200e664e25
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/machine_cse_illegal_hoist.ll
@@ -0,0 +1,52 @@
+; RUN: llc -O3 < %s | FileCheck %s
+;
+;  Check ADRP instr is not hoisted to entry basic block
+;  which may throw exception.
+;
+; CHECK: adrp
+; CHECK: adrp
+; CHECK: adrp
+
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64-arm-none-eabi"
+
+@var = hidden local_unnamed_addr global i32 0, align 4
+@_ZTIi = external dso_local constant i8*
+declare dso_local void @_Z2fnv() local_unnamed_addr #1
+declare dso_local i32 @__gxx_personality_v0(...)
+declare i32 @llvm.eh.typeid.for(i8*) #2
+declare dso_local i8* @__cxa_begin_catch(i8*) local_unnamed_addr
+declare dso_local void @__cxa_end_catch() local_unnamed_addr
+
+define hidden i32 @_Z7examplev() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
+entry:
+  invoke void @_Z2fnv() to label %try.cont unwind label %lpad
+
+lpad:                                             ; preds = %entry
+  %0 = landingpad { i8*, i32 }
+          catch i8* bitcast (i8** @_ZTIi to i8*)
+          catch i8* null
+  %1 = extractvalue { i8*, i32 } %0, 0
+  %2 = extractvalue { i8*, i32 } %0, 1
+  %3 = tail call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIi to i8*))
+  %matches = icmp eq i32 %2, %3
+  %4 = tail call i8* @__cxa_begin_catch(i8* %1)
+  %5 = load i32, i32* @var, align 4
+  br i1 %matches, label %catch1, label %catch
+
+catch1:                                           ; preds = %lpad
+  %or3 = or i32 %5, 4
+  store i32 %or3, i32* @var, align 4
+  tail call void @__cxa_end_catch()
+  br label %try.cont
+
+try.cont:                                         ; preds = %entry, %catch1, %catch
+  %6 = load i32, i32* @var, align 4
+  ret i32 %6
+
+catch:                                            ; preds = %lpad
+  %or = or i32 %5, 8
+  store i32 %or, i32* @var, align 4
+  tail call void @__cxa_end_catch()
+  br label %try.cont
+}