[PATCH] D43859: [GlobalOpt] don't change CC of musttail calle(e|r) PR36546
Fedor Indutny via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Feb 28 14:25:53 PST 2018
indutny updated this revision to Diff 136400.
indutny added a comment.
Fix test.
---
Sorry, looks like I forgot to add `internal` to the `foo2` (or removed it by mistake when rebasing).
https://reviews.llvm.org/D43859
Files:
lib/Transforms/IPO/GlobalOpt.cpp
test/Transforms/GlobalOpt/musttail_cc.ll
Index: test/Transforms/GlobalOpt/musttail_cc.ll
===================================================================
--- /dev/null
+++ test/Transforms/GlobalOpt/musttail_cc.ll
@@ -0,0 +1,34 @@
+; RUN: opt < %s -globalopt -S | FileCheck %s
+; PR36546
+
+; Check that musttail callee preserves its calling convention
+
+define i32 @test(i32 %a) {
+ ; CHECK: %ca = musttail call i32 @foo(i32 %a)
+ %ca = musttail call i32 @foo(i32 %a)
+ ret i32 %ca
+}
+
+; CHECK-LABEL: define internal i32 @foo(i32 %a)
+define internal i32 @foo(i32 %a) {
+ ret i32 %a
+}
+
+; Check that musttail caller preserves its calling convention
+
+define i32 @test2(i32 %a) {
+ %ca = call i32 @foo1(i32 %a)
+ ret i32 %ca
+}
+
+; CHECK-LABEL: define internal i32 @foo1(i32 %a)
+define internal i32 @foo1(i32 %a) {
+ ; CHECK: %ca = musttail call i32 @foo2(i32 %a)
+ %ca = musttail call i32 @foo2(i32 %a)
+ ret i32 %ca
+}
+
+; CHECK-LABEL: define internal i32 @foo2(i32 %a)
+define internal i32 @foo2(i32 %a) {
+ ret i32 %a
+}
Index: lib/Transforms/IPO/GlobalOpt.cpp
===================================================================
--- lib/Transforms/IPO/GlobalOpt.cpp
+++ lib/Transforms/IPO/GlobalOpt.cpp
@@ -2115,8 +2115,31 @@
/// GHC, or anyregcc.
static bool hasChangeableCC(Function *F) {
CallingConv::ID CC = F->getCallingConv();
+
// FIXME: Is it worth transforming x86_stdcallcc and x86_fastcallcc?
- return CC == CallingConv::C || CC == CallingConv::X86_ThisCall;
+ if (CC != CallingConv::C && CC != CallingConv::X86_ThisCall)
+ return false;
+
+ // FIXME: Change CC for the whole chain of musttail calls when possible.
+ //
+ // Can't change CC of the function that either has musttail calls, or is a
+ // musttail callee itself
+ for (User *U : F->users()) {
+ if (isa<BlockAddress>(U))
+ continue;
+ CallInst* CI = dyn_cast<CallInst>(U);
+ if (!CI)
+ continue;
+
+ if (CI->isMustTailCall())
+ return false;
+ }
+
+ for (BasicBlock &BB : *F)
+ if (BB.getTerminatingMustTailCall())
+ return false;
+
+ return true;
}
/// Return true if the block containing the call site has a BlockFrequency of
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