Mark that the return is using EAX so that we don't use it for some other
purpose. Fixes PR9080!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124903 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocFast.cpp b/lib/CodeGen/RegAllocFast.cpp
index 5793477..15036e3 100644
--- a/lib/CodeGen/RegAllocFast.cpp
+++ b/lib/CodeGen/RegAllocFast.cpp
@@ -735,6 +735,27 @@
void RAFast::AllocateBasicBlock() {
DEBUG(dbgs() << "\nAllocating " << *MBB);
+ // FIXME: This should probably be added by instruction selection instead?
+ // If the last instruction in the block is a return, make sure to mark it as
+ // using all of the live-out values in the function. Things marked both call
+ // and return are tail calls; do not do this for them. The tail callee need
+ // not take the same registers as input that it produces as output, and there
+ // are dependencies for its input registers elsewhere.
+ if (!MBB->empty() && MBB->back().getDesc().isReturn() &&
+ !MBB->back().getDesc().isCall()) {
+ MachineInstr *Ret = &MBB->back();
+
+ for (MachineRegisterInfo::liveout_iterator
+ I = MF->getRegInfo().liveout_begin(),
+ E = MF->getRegInfo().liveout_end(); I != E; ++I) {
+ assert(TargetRegisterInfo::isPhysicalRegister(*I) &&
+ "Cannot have a live-out virtual register.");
+
+ // Add live-out registers as implicit uses.
+ Ret->addRegisterKilled(*I, TRI, true);
+ }
+ }
+
PhysRegState.assign(TRI->getNumRegs(), regDisabled);
assert(LiveVirtRegs.empty() && "Mapping not cleared form last block?");
diff --git a/test/CodeGen/X86/2011-02-04-FastRegallocNoFP.ll b/test/CodeGen/X86/2011-02-04-FastRegallocNoFP.ll
new file mode 100644
index 0000000..cedd6a2
--- /dev/null
+++ b/test/CodeGen/X86/2011-02-04-FastRegallocNoFP.ll
@@ -0,0 +1,14 @@
+; RUN: llc -O0 < %s | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-unknown-linux-gnu"
+
+declare i32 @foo()
+
+define i32 @bar() nounwind {
+; CHECK: bar
+; CHECK-NOT: pop.*ax
+ %call = call i32 @foo()
+ ret i32 %call
+}
+