[remark][diagnostics] [codegen] Fix PR44896

This patch fixes PR44896. For IR input files, option fdiscard-value-names
should be ignored as we need named values in loadModule().
Commit 60d3947922 sets this option after loadModule() where valued names
already created. This creates an inconsistent state in setNameImpl()
that leads to a seg fault.
This patch forces fdiscard-value-names to be false for IR input files.

This patch also emits a warning of "ignoring -fdiscard-value-names" if
option fdiscard-value-names is explictly enabled in the commandline for
IR input files.

Differential Revision: https://reviews.llvm.org/D74878

(cherry picked from commit 11857d49948b845dcfd7c7f78595095e3add012d)

1 files changed, 3 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp
index 7065e78f19a..20ebaf3578d 100644
--- a/clang/lib/CodeGen/CodeGenAction.cpp
+++ b/clang/lib/CodeGen/CodeGenAction.cpp
@@ -1146,6 +1146,9 @@ void CodeGenAction::ExecuteAction() {
                            CI.getTargetOpts(), CI.getLangOpts(),
                            CI.getFrontendOpts().ShowTimers,
                            std::move(LinkModules), *VMContext, nullptr);
+    // PR44896: Force DiscardValueNames as false. DiscardValueNames cannot be
+    // true here because the valued names are needed for reading textual IR.
+    Ctx.setDiscardValueNames(false);
     Ctx.setDiagnosticHandler(
         std::make_unique<ClangDiagnosticHandler>(CodeGenOpts, &Result));