[llvm] r273188 - InstCombine: Don't strip convergent from intrinsic callsites

[Matt Arsenault via llvm-commits]

Author: arsenm
Date: Mon Jun 20 14:04:44 2016
New Revision: 273188

URL: http://llvm.org/viewvc/llvm-project?rev=273188&view=rev
Log:
InstCombine: Don't strip convergent from intrinsic callsites

Specific instances of intrinsic calls may want to be convergent, such
as certain register reads but the intrinsic declaration is not.

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
    llvm/trunk/test/Transforms/InstCombine/convergent.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp?rev=273188&r1=273187&r2=273188&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp Mon Jun 20 14:04:44 2016
@@ -2507,7 +2507,8 @@ Instruction *InstCombiner::visitCallSite
 
   if (Function *CalleeF = dyn_cast<Function>(Callee)) {
     // Remove the convergent attr on calls when the callee is not convergent.
-    if (CS.isConvergent() && !CalleeF->isConvergent()) {
+    if (CS.isConvergent() && !CalleeF->isConvergent() &&
+        !CalleeF->isIntrinsic()) {
       DEBUG(dbgs() << "Removing convergent attr from instr "
                    << CS.getInstruction() << "\n");
       CS.setNotConvergent();

Modified: llvm/trunk/test/Transforms/InstCombine/convergent.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/convergent.ll?rev=273188&r1=273187&r2=273188&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/convergent.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/convergent.ll Mon Jun 20 14:04:44 2016
@@ -3,6 +3,8 @@
 declare i32 @k() convergent
 declare i32 @f()
 
+declare i64 @llvm.read_register.i64(metadata) nounwind
+
 define i32 @extern() {
   ; Convergent attr shouldn't be removed here; k is convergent.
   ; CHECK: call i32 @k() [[CONVERGENT_ATTR:#[0-9]+]]
@@ -30,4 +32,13 @@ define i32 @indirect_call(i32 ()* %f) {
   ret i32 %a
 }
 
+; do not remove from convergent intrinsic call sites
+; CHECK-LABEL: @convergent_intrinsic_call(
+; CHECK: call i64 @llvm.read_register.i64(metadata !0) [[CONVERGENT_ATTR]]
+define i64 @convergent_intrinsic_call() {
+  %val = call i64 @llvm.read_register.i64(metadata !0) convergent
+  ret i64 %val
+}
+
 ; CHECK: [[CONVERGENT_ATTR]] = { convergent }
+!0 = !{!"foo"}