[llvm] 873c0d0 - [ThinLTO/LowerTypeTests] Handle unpromoted local type ids

[Teresa Johnson via llvm-commits]

Author: Teresa Johnson
Date: 2020-03-02T09:31:44-08:00
New Revision: 873c0d0786dcf22f4af39f65df824917f70f2170

URL: https://github.com/llvm/llvm-project/commit/873c0d0786dcf22f4af39f65df824917f70f2170
DIFF: https://github.com/llvm/llvm-project/commit/873c0d0786dcf22f4af39f65df824917f70f2170.diff

LOG: [ThinLTO/LowerTypeTests] Handle unpromoted local type ids

Summary:
Fixes an issue that cropped up after the changes in D73242 to delay
the lowering of type tests. LTT couldn't handle any type tests with
non-string type id (which happens for local vtables, which we try to
promote during the compile step but cannot always when there are no
exported symbols).

We can simply treat the same as having an Unknown resolution, which
delays their lowering, still allowing such type tests to be used in
subsequent optimization (e.g. planned usage during ICP). The final
lowering which simply removes these handles them fine.

Beefed up an existing ThinLTO test for such unpromoted type ids so that
the internal vtable isn't removed before lower type tests, which hides
the problem.

Reviewers: evgeny777, pcc

Subscribers: inglorion, hiraditya, steven_wu, dexonsmith, aganea, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75201

Added: 
    

Modified: 
    llvm/lib/Transforms/IPO/LowerTypeTests.cpp
    llvm/test/ThinLTO/X86/nodevirt-nonpromoted-typeid.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
index 7c26f156d4c9..cb9b29a71895 100644
--- a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
+++ b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
@@ -1040,9 +1040,11 @@ void LowerTypeTestsModule::importTypeTest(CallInst *CI) {
     report_fatal_error("Second argument of llvm.type.test must be metadata");
 
   auto TypeIdStr = dyn_cast<MDString>(TypeIdMDVal->getMetadata());
+  // If this is a local unpromoted type, which doesn't have a metadata string,
+  // treat as Unknown and delay lowering, so that we can still utilize it for
+  // later optimizations.
   if (!TypeIdStr)
-    report_fatal_error(
-        "Second argument of llvm.type.test must be a metadata string");
+    return;
 
   TypeIdLowering TIL = importTypeId(TypeIdStr->getString());
   Value *Lowered = lowerTypeTestCall(TypeIdStr, CI, TIL);

diff  --git a/llvm/test/ThinLTO/X86/nodevirt-nonpromoted-typeid.ll b/llvm/test/ThinLTO/X86/nodevirt-nonpromoted-typeid.ll
index 611a424143ac..3669db72fa00 100644
--- a/llvm/test/ThinLTO/X86/nodevirt-nonpromoted-typeid.ll
+++ b/llvm/test/ThinLTO/X86/nodevirt-nonpromoted-typeid.ll
@@ -33,6 +33,8 @@
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-grtev4-linux-gnu"
 
+ at llvm.global_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @g, i8* null }]
+
 %struct.D = type { i32 (...)** }
 
 @_ZTV1D = internal constant { [3 x i8*] } { [3 x i8*] [i8* null, i8* undef, i8* bitcast (i32 (%struct.D*, i32)* @_ZN1D1mEi to i8*)] }, !type !3
@@ -57,6 +59,23 @@ entry:
 ; CHECK-IR-LABEL: ret i32
 ; CHECK-IR-LABEL: }
 
+; Function Attrs: inlinehint nounwind uwtable
+define internal void @_ZN1DC2Ev(%struct.D* %this) unnamed_addr align 2 {
+entry:
+  %this.addr = alloca %struct.D*, align 8
+  store %struct.D* %this, %struct.D** %this.addr, align 8
+  %this1 = load %struct.D*, %struct.D** %this.addr
+  %0 = bitcast %struct.D* %this1 to i32 (...)***
+  store i32 (...)** bitcast (i8** getelementptr inbounds ({ [3 x i8*] }, { [3 x i8*] }* @_ZTV1D, i64 0, inrange i32 0, i64 2) to i32 (...)**), i32 (...)*** %0, align 8
+  ret void
+}
+
+define internal void @g() section ".text.startup" {
+  %d = alloca %struct.D, align 8
+  call void @_ZN1DC2Ev(%struct.D* %d)
+  ret void
+}
+
 declare i1 @llvm.type.test(i8*, metadata)
 declare void @llvm.assume(i1)