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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@273188 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 1aa4b87bb929aa53284e5016fc82b313f53510b0..c2cf21d5221437a860974f46e8ef29c275f7f708 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -2507,7 +2507,8 @@ Instruction *InstCombiner::visitCallSite(CallSite CS) {
 
   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();

diff --git a/test/Transforms/InstCombine/convergent.ll b/test/Transforms/InstCombine/convergent.ll
index 4ed40d81badc3c1ed25771bf75cafe154378634e..d4484cf4567ea3c07ccd4b893d2ac814cd5b498c 100644 (file)
--- a/test/Transforms/InstCombine/convergent.ll
+++ b/test/Transforms/InstCombine/convergent.ll
@@ -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"}