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Create PHI node for the return value only when the return value has uses. 

Summary:
Currently, a phi node is created in the normal destination to unify the return values from promoted calls and the original indirect call. This patch makes this phi node to be created only when the return value has uses.

This patch is necessary to generate valid code, as compiler crashes with the attached test case without this patch. Without this patch, an illegal phi node that has no incoming value from `entry`/`catch` is created in `cleanup` block.

I think existing implementation is good as far as there is at least one use of the original indirect call. `insertCallRetPHI` creates a new phi node in the normal destination block only when the original indirect call dominates its use and the normal destination block. Otherwise, `fixupPHINodeForNormalDest` will handle the unification of return values naturally without creating a new phi node. However, if there's no use, `insertCallRetPHI` still creates a new phi node even when the original indirect call does not dominate the normal destination block, because `getCallRetPHINode` returns false.

Reviewers: xur, davidxl, danielcdh

Reviewed By: xur

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D37176

llvm-svn: 311906
This commit is contained in:
Taewook Oh 2017-08-28 18:57:00 +00:00
parent 0a539b5859
commit 572f45a3c8
3 changed files with 74 additions and 2 deletions
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3
llvm/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp
View File

@ -508,6 +508,9 @@ static void insertCallRetPHI(Instruction *Inst, Instruction *CallResult,
if (Inst->getType()->isVoidTy())
return;
if (Inst->use_empty())
return;
BasicBlock *RetValBB = CallResult->getParent();
BasicBlock *PHIBB;

4
llvm/test/Transforms/PGOProfile/icp_covariant_call_return.ll
View File

@ -12,7 +12,7 @@ declare noalias i8* @_Znwm(i64)
declare void @_ZN1DC2Ev(%struct.D*);
declare %struct.Derived* @_ZN1D4funcEv(%struct.D*);
define i32 @bar() {
define %struct.Base* @bar() {
entry:
%call = call noalias i8* @_Znwm(i64 8)
%tmp = bitcast i8* %call to %struct.D*
@ -36,7 +36,7 @@ entry:
; ICALL-PROM:if.end.icp:
; ICALL-PROM: [[PHI_RET:%[0-9]+]] = phi %struct.Base* [ %call1, %if.false.orig_indirect ], [ [[DIRCALL_RET_CAST]], %if.true.direct_targ ]
%call1 = call %struct.Base* %tmp3(%struct.B* %tmp1), !prof !1
ret i32 0
ret %struct.Base* %call1
}
!1 = !{!"VP", i32 0, i64 12345, i64 -3913987384944532146, i64 12345}

69
llvm/test/Transforms/PGOProfile/icp_invoke_nouse.ll Normal file
View File

@ -0,0 +1,69 @@
; RUN: opt < %s -icp-lto -pgo-icall-prom -S | FileCheck %s --check-prefix=ICP
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
@_ZTISt9exception = external constant i8*
@pfptr = global i32()* null, align 8
define internal i32 @_ZL4bar1v() !PGOFuncName !0 {
entry:
ret i32 100
}
; Function Attrs: uwtable
define i32 @_Z3fooi(i32 %x) local_unnamed_addr personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
entry:
%tobool = icmp eq i32 %x, 0
br i1 %tobool, label %if.end, label %cleanup
if.end: ; preds = %entry
%fptr = load i32 ()*, i32 ()** @pfptr, align 8
; ICP: [[BITCAST_IC1:%[0-9]+]] = bitcast i32 ()* %fptr to i8*
; ICP: [[CMP_IC1:%[0-9]+]] = icmp eq i8* [[BITCAST_IC1]], bitcast (i32 ()* @_ZL4bar1v to i8*)
; ICP: br i1 [[CMP_IC1]], label %[[TRUE_LABEL_IC1:.*]], label %[[FALSE_LABEL_IC1:.*]], !prof [[BRANCH_WEIGHT:![0-9]+]]
; ICP:[[TRUE_LABEL_IC1]]:
; ICP: invoke i32 @_ZL4bar1v()
; ICP: to label %[[DCALL_NORMAL_DEST_IC1:.*]] unwind label %lpad
; ICP:[[FALSE_LABEL_IC1]]:
%call = invoke i32 %fptr()
to label %cleanup unwind label %lpad, !prof !1
; ICP:[[DCALL_NORMAL_DEST_IC1]]:
; ICP: br label %cleanup
lpad: ; preds = %if.end
%0 = landingpad { i8*, i32 }
cleanup
catch i8* bitcast (i8** @_ZTISt9exception to i8*)
%1 = extractvalue { i8*, i32 } %0, 1
%2 = tail call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTISt9exception to i8*))
%matches = icmp eq i32 %1, %2
br i1 %matches, label %catch, label %ehcleanup
catch: ; preds = %lpad
%3 = extractvalue { i8*, i32 } %0, 0
%4 = tail call i8* @__cxa_begin_catch(i8* %3)
tail call void @__cxa_end_catch()
br label %cleanup
cleanup: ; preds = %catch, %if.end, %entry
; ICP-NOT: %[0-9]+ = phi
ret i32 0
ehcleanup: ; preds = %lpad
resume { i8*, i32 } %0
}
declare i32 @_Z3barv() local_unnamed_addr
declare i32 @__gxx_personality_v0(...)
; Function Attrs: nounwind readnone
declare i32 @llvm.eh.typeid.for(i8*)
declare i8* @__cxa_begin_catch(i8*) local_unnamed_addr
declare void @__cxa_end_catch() local_unnamed_addr
!0 = !{!"invoke.ll:_ZL4bar1v"}
!1 = !{!"VP", i32 0, i64 10000, i64 -2732222848796217051, i64 10000}