TargetInstrInfo: squelch a signedness warning on MSVC

[artagnon]

Follow up on 9468de4 (TargetInstrInfo: make getOperandLatency return optional (NFC)) to squelch a signedness warning on MSVC, reported by Simon Pilgrim.

[llvmbot]

@llvm/pr-subscribers-backend-arm

Author: Ramkumar Ramachandra (artagnon)

Changes

Follow up on 9468de4 (TargetInstrInfo: make getOperandLatency return optional (NFC)) to squelch a signedness warning on MSVC, reported by Simon Pilgrim.

---

Full diff: https://github.com/llvm/llvm-project/pull/74078.diff

2 Files Affected:

• (modified) llvm/include/llvm/MC/MCInstrItineraries.h (+1-1)
• (modified) llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp (+1-1)

diff --git a/llvm/include/llvm/MC/MCInstrItineraries.h b/llvm/include/llvm/MC/MCInstrItineraries.h
index b17c41ce3aa4a14..d1c2e788ee8105c 100644
--- a/llvm/include/llvm/MC/MCInstrItineraries.h
+++ b/llvm/include/llvm/MC/MCInstrItineraries.h
@@ -220,7 +220,7 @@ class InstrItineraryData {
       return std::nullopt;
 
     UseCycle = *DefCycle - *UseCycle + 1;
-    if (UseCycle > 0 &&
+    if (UseCycle > 0u &&
         hasPipelineForwarding(DefClass, DefIdx, UseClass, UseIdx))
       // FIXME: This assumes one cycle benefit for every pipeline forwarding.
       UseCycle = *UseCycle - 1;
diff --git a/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp b/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
index 94f34b127696609..ce65c8e5245b19f 100644
--- a/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -4110,7 +4110,7 @@ std::optional<unsigned> ARMBaseInstrInfo::getOperandLatency(
     return std::nullopt;
 
   UseCycle = *DefCycle - *UseCycle + 1;
-  if (UseCycle > 0) {
+  if (UseCycle > 0u) {
     if (LdmBypass) {
       // It's a variable_ops instruction so we can't use DefIdx here. Just use
       // first def operand.

[RKSimon]

This will help, but there are a LOT of these warnings in other files - I don't have the time to address these right now. Ideally you'd be able to find a buildbot that lists them in the build stdout (and not just the header line)

[RKSimon]

Actually https://lab.llvm.org/buildbot/#/builders/216/builds/31206/steps/6/logs/stdio should give you a more complete list

[artagnon]

Thanks. I looked at the build log, and all the warnings are coming from including MCInstrItineraries.h, and the warning is on line 223, which I've fixed.

[RKSimon]

LGTM as a first pass