ThinLTO: handles modules with empty summaries

We need to add an entry in the combined-index for modules that have
a hash but otherwise empty summary, this is needed so that we can
get the hash for the module.

Also, if no entry is present in the combined index for a module, we
need to skip it when trying to compute a cache entry.

Differential Revision: https://reviews.llvm.org/D25300

llvm-svn: 283654

2 files changed, 43 insertions, 0 deletions

diff --git a/llvm/test/ThinLTO/X86/Inputs/empty_module_with_cache.ll b/llvm/test/ThinLTO/X86/Inputs/empty_module_with_cache.ll
new file mode 100644
index 00000000000..1c55e078ea3
--- /dev/null
+++ b/llvm/test/ThinLTO/X86/Inputs/empty_module_with_cache.ll
@@ -0,0 +1,8 @@
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.11.0"
+
+
+define i32 @main() {
+entry:
+  ret i32 0
+}
diff --git a/llvm/test/ThinLTO/X86/empty_module_with_cache.ll b/llvm/test/ThinLTO/X86/empty_module_with_cache.ll
new file mode 100644
index 00000000000..c6274515630
--- /dev/null
+++ b/llvm/test/ThinLTO/X86/empty_module_with_cache.ll
@@ -0,0 +1,35 @@
+; RUN: opt -module-hash -module-summary %s -o %t.bc
+; RUN: opt -module-hash -module-summary %p/Inputs/empty_module_with_cache.ll -o %t2.bc
+
+; Verify that enabling caching is working, even if the module is empty
+; RUN: rm -Rf %t.cache && mkdir %t.cache
+; RUN: llvm-lto -thinlto-action=run %t2.bc  %t.bc -exported-symbol=main -thinlto-cache-dir %t.cache
+; RUN: ls %t.cache/llvmcache.timestamp
+; RUN: ls %t.cache | count 3
+
+; Verify that enabling caching is working with llvm-lto2
+; RUN: rm -Rf %t.cache && mkdir %t.cache
+; RUN: llvm-lto2 -o %t.o %t2.bc  %t.bc -cache-dir %t.cache \
+; RUN:  -r=%t2.bc,_main,plx
+; RUN: ls %t.cache | count 2
+
+; Same, but without hash, the index will be empty and caching should not happen
+
+; RUN: opt -module-summary %s -o %t.bc
+; RUN: opt -module-summary %p/Inputs/empty_module_with_cache.ll -o %t2.bc
+
+; Verify that caching is disabled for module without hash
+; RUN: rm -Rf %t.cache && mkdir %t.cache
+; RUN: llvm-lto -thinlto-action=run %t2.bc  %t.bc -exported-symbol=main -thinlto-cache-dir %t.cache
+; RUN: ls %t.cache/llvmcache.timestamp
+; RUN: ls %t.cache | count 2
+
+; Verify that caching is disabled for module without hash, with llvm-lto2
+; RUN: rm -Rf %t.cache && mkdir %t.cache
+; RUN: llvm-lto2 -o %t.o %t2.bc  %t.bc -cache-dir %t.cache \
+; RUN:  -r=%t2.bc,_main,plx
+; RUN: ls %t.cache | count 1
+
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.11.0"