AMDGPU: Avoid overwriting saved PC
Summary:
An outstanding load with same destination sgpr as call could cause PC to be
updated with junk value on return.
Reviewers: arsenm, rampitec
Reviewed By: arsenm
Subscribers: kzhuravl, jvesely, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D69474
diff --git a/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp b/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp
index dcb04e4..e84e948 100644
--- a/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp
@@ -939,19 +939,33 @@
}
if (MI.isCall() && callWaitsOnFunctionEntry(MI)) {
- // Don't bother waiting on anything except the call address. The function
- // is going to insert a wait on everything in its prolog. This still needs
- // to be careful if the call target is a load (e.g. a GOT load).
+ // The function is going to insert a wait on everything in its prolog.
+ // This still needs to be careful if the call target is a load (e.g. a GOT
+ // load). We also need to check WAW depenancy with saved PC.
Wait = AMDGPU::Waitcnt();
int CallAddrOpIdx =
AMDGPU::getNamedOperandIdx(MI.getOpcode(), AMDGPU::OpName::src0);
- RegInterval Interval = ScoreBrackets.getRegInterval(&MI, TII, MRI, TRI,
- CallAddrOpIdx, false);
- for (signed RegNo = Interval.first; RegNo < Interval.second; ++RegNo) {
+ RegInterval CallAddrOpInterval = ScoreBrackets.getRegInterval(
+ &MI, TII, MRI, TRI, CallAddrOpIdx, false);
+
+ for (signed RegNo = CallAddrOpInterval.first;
+ RegNo < CallAddrOpInterval.second; ++RegNo)
ScoreBrackets.determineWait(
LGKM_CNT, ScoreBrackets.getRegScore(RegNo, LGKM_CNT), Wait);
+
+ int RtnAddrOpIdx =
+ AMDGPU::getNamedOperandIdx(MI.getOpcode(), AMDGPU::OpName::dst);
+ if (RtnAddrOpIdx != -1) {
+ RegInterval RtnAddrOpInterval = ScoreBrackets.getRegInterval(
+ &MI, TII, MRI, TRI, RtnAddrOpIdx, false);
+
+ for (signed RegNo = RtnAddrOpInterval.first;
+ RegNo < RtnAddrOpInterval.second; ++RegNo)
+ ScoreBrackets.determineWait(
+ LGKM_CNT, ScoreBrackets.getRegScore(RegNo, LGKM_CNT), Wait);
}
+
} else {
// FIXME: Should not be relying on memoperands.
// Look at the source operands of every instruction to see if