[llvm] 3c54762 - [funcattrs] Consistently check call site attributes

[Philip Reames via llvm-commits]

Author: Philip Reames
Date: 2021-04-19T13:20:50-07:00
New Revision: 3c54762226ed9bcb84dfdef9f8e6e6a2c6a971a0

URL: https://github.com/llvm/llvm-project/commit/3c54762226ed9bcb84dfdef9f8e6e6a2c6a971a0
DIFF: https://github.com/llvm/llvm-project/commit/3c54762226ed9bcb84dfdef9f8e6e6a2c6a971a0.diff

LOG: [funcattrs] Consistently check call site attributes

This is mostly stylistic cleanup after D100226, but not entirely. When skimming the code, I found one case where we weren't accounting for attributes on the callsite at all. I'm also suspicious we had some latent bugs related to operand bundles (which are supposed to be able to *override* attributes on declarations), but I don't have concrete test cases for those, just suspicions.

Aside: The only case left in the file which directly checks attributes on the declaration is the norecurse logic. I left that because I didn't understand it; it looks obviously wrong, so I suspect I'm misinterpreting the intended semantics of the attribute.

Differential Revision: https://reviews.llvm.org/D100689

Added: 
    

Modified: 
    llvm/lib/Transforms/IPO/FunctionAttrs.cpp
    llvm/test/Transforms/FunctionAttrs/noreturn.ll
    llvm/test/Transforms/FunctionAttrs/willreturn-callsites.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
index 0202046158b14..64966bddfe0c4 100644
--- a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -1271,15 +1271,10 @@ static bool InstrBreaksNoFree(Instruction &I, const SCCNodeSet &SCCNodes) {
   if (CB->hasFnAttr(Attribute::NoFree))
     return false;
 
-  Function *Callee = CB->getCalledFunction();
-  if (!Callee)
-    return true;
-
-  if (Callee->doesNotFreeMemory())
-    return false;
-
-  if (SCCNodes.contains(Callee))
-    return false;
+  // Speculatively assume in SCC.
+  if (Function *Callee = CB->getCalledFunction())
+    if (SCCNodes.contains(Callee))
+      return false;
 
   return true;
 }
@@ -1403,10 +1398,8 @@ static bool addNoRecurseAttrs(const SCCNodeSet &SCCNodes) {
 }
 
 static bool instructionDoesNotReturn(Instruction &I) {
-  if (auto *CB = dyn_cast<CallBase>(&I)) {
-    Function *Callee = CB->getCalledFunction();
-    return Callee && Callee->doesNotReturn();
-  }
+  if (auto *CB = dyn_cast<CallBase>(&I))
+    return CB->hasFnAttr(Attribute::NoReturn);
   return false;
 }
 
@@ -1517,13 +1510,6 @@ static bool InstrBreaksNoSync(Instruction &I, const SCCNodeSet &SCCNodes) {
   if (CB->hasFnAttr(Attribute::NoSync))
     return false;
 
-  // readnone + not convergent implies nosync
-  // (This is needed to initialize inference from declarations which aren't
-  //  explicitly nosync, but are readnone and not convergent.)
-  if (CB->hasFnAttr(Attribute::ReadNone) &&
-      !CB->hasFnAttr(Attribute::Convergent))
-    return false;
-
   // Non volatile memset/memcpy/memmoves are nosync
   // NOTE: Only intrinsics with volatile flags should be handled here.  All
   // others should be marked in Intrinsics.td.

diff  --git a/llvm/test/Transforms/FunctionAttrs/noreturn.ll b/llvm/test/Transforms/FunctionAttrs/noreturn.ll
index acc538d3cceef..098788f93af8f 100644
--- a/llvm/test/Transforms/FunctionAttrs/noreturn.ll
+++ b/llvm/test/Transforms/FunctionAttrs/noreturn.ll
@@ -64,3 +64,10 @@ define i32 @caller6() naked {
 define i32 @alreadynoreturn() noreturn {
   unreachable
 }
+
+; CHECK: Function Attrs: {{.*}}noreturn
+; CHECK-NEXT: @callsite_noreturn()
+define void @callsite_noreturn() {
+  call i32 @f() noreturn
+  ret void
+}

diff  --git a/llvm/test/Transforms/FunctionAttrs/willreturn-callsites.ll b/llvm/test/Transforms/FunctionAttrs/willreturn-callsites.ll
index 10fd6930d4e58..1dbeffc927cd3 100644
--- a/llvm/test/Transforms/FunctionAttrs/willreturn-callsites.ll
+++ b/llvm/test/Transforms/FunctionAttrs/willreturn-callsites.ll
@@ -1,4 +1,4 @@
-; RUN: opt -function-attrs -S %s | FileCheck %s
+; RUN: opt -inferattrs -function-attrs -S %s | FileCheck %s
 
 declare void @decl_readonly() readonly
 declare void @decl_readnone() readnone