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13c5bb4a2e
Presently, CodeGenPrepare deletes all nearly empty (only phi and branch) basic blocks. This pass can delete loop preheaders which frequently creates critical edges. A preheader can be a convenient place to spill registers to the stack. If the entrance to a loop body is a critical edge, then spills may occur in the loop body rather than immediately before it. This patch protects loop preheaders from deletion in CodeGenPrepare even if they are nearly empty. Since the patch alters the CFG, it affects a large number of test cases. In most cases, the changes are merely cosmetic (basic blocks have different names or instruction orders change slightly). I am somewhat concerned about the test/CodeGen/Mips/brdelayslot.ll test case. If the loop preheader is not deleted, then the MIPS backend does not take advantage of a branch delay slot. Consequently, I would like some close review by a MIPS expert. The patch also partially subsumes D16893 from George Burgess IV. George correctly notes that CodeGenPrepare does not actually preserve the dominator tree. I think the dominator tree was usually not valid when CodeGenPrepare ran, but I am using LoopInfo to mark preheaders, so the dominator tree is now always valid before CodeGenPrepare. Author: Tom Jablin (tjablin) Reviewers: hfinkel george.burgess.iv vkalintiris dsanders kbarton cycheng http://reviews.llvm.org/D16984 llvm-svn: 265397
194 lines
9.2 KiB
LLVM
194 lines
9.2 KiB
LLVM
; RUN: llc < %s -O1 -mtriple thumbv7-apple-ios6 | FileCheck %s
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; Just make sure no one tries to make the assumption that the normal edge of an
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; invoke is never a critical edge. Previously, this code would assert.
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%struct.__CFString = type opaque
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declare void @bar(%struct.__CFString*, %struct.__CFString*)
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define noalias i8* @foo(i8* nocapture %inRefURL) noreturn ssp personality i8* bitcast (i32 (...)* @__gxx_personality_sj0 to i8*) {
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entry:
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%call = tail call %struct.__CFString* @bar3()
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%call2 = invoke i8* @bar2()
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to label %for.cond unwind label %lpad
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for.cond: ; preds = %entry, %for.cond
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invoke void @bar(%struct.__CFString* undef, %struct.__CFString* null)
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to label %for.cond unwind label %lpad5
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lpad: ; preds = %entry
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%0 = landingpad { i8*, i32 }
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cleanup
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%1 = extractvalue { i8*, i32 } %0, 0
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%2 = extractvalue { i8*, i32 } %0, 1
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br label %ehcleanup
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lpad5: ; preds = %for.cond
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%3 = landingpad { i8*, i32 }
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cleanup
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%4 = extractvalue { i8*, i32 } %3, 0
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%5 = extractvalue { i8*, i32 } %3, 1
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invoke void @release(i8* %call2)
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to label %ehcleanup unwind label %terminate.lpad.i.i16
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terminate.lpad.i.i16: ; preds = %lpad5
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%6 = landingpad { i8*, i32 }
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catch i8* null
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tail call void @terminatev() noreturn nounwind
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unreachable
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ehcleanup: ; preds = %lpad5, %lpad
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%exn.slot.0 = phi i8* [ %1, %lpad ], [ %4, %lpad5 ]
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%ehselector.slot.0 = phi i32 [ %2, %lpad ], [ %5, %lpad5 ]
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%7 = bitcast %struct.__CFString* %call to i8*
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invoke void @release(i8* %7)
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to label %_ZN5SmartIPK10__CFStringED1Ev.exit unwind label %terminate.lpad.i.i
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terminate.lpad.i.i: ; preds = %ehcleanup
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%8 = landingpad { i8*, i32 }
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catch i8* null
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tail call void @terminatev() noreturn nounwind
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unreachable
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_ZN5SmartIPK10__CFStringED1Ev.exit: ; preds = %ehcleanup
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%lpad.val = insertvalue { i8*, i32 } undef, i8* %exn.slot.0, 0
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%lpad.val12 = insertvalue { i8*, i32 } %lpad.val, i32 %ehselector.slot.0, 1
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resume { i8*, i32 } %lpad.val12
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}
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declare %struct.__CFString* @bar3()
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declare i8* @bar2()
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declare i32 @__gxx_personality_sj0(...)
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declare void @release(i8*)
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declare void @terminatev()
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; Make sure that the instruction DemoteRegToStack inserts to reload
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; %call.i.i.i14.i.i follows the instruction that saves the value to the stack in
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; basic block %entry.do.body.i.i.i_crit_edge.
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; Previously, DemoteRegToStack would insert a load instruction into the entry
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; block to reload %call.i.i.i14.i.i before the phi instruction (%0) in block
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; %do.body.i.i.i.
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; CHECK-LABEL: __Z4foo1c:
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; CHECK: blx __Znwm
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; CHECK: {{.*}}@ %do.body.i.i.i.preheader
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; CHECK: str r0, [sp, [[OFFSET:#[0-9]+]]]
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; CHECK: {{.*}}@ %do.body.i.i.i
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; CHECK: ldr [[R0:r[0-9]+]], [sp, [[OFFSET]]]
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; CHECK: cbz [[R0]]
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%"class.std::__1::basic_string" = type { %"class.std::__1::__compressed_pair" }
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%"class.std::__1::__compressed_pair" = type { %"class.std::__1::__libcpp_compressed_pair_imp" }
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%"class.std::__1::__libcpp_compressed_pair_imp" = type { %"struct.std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::__rep" }
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%"struct.std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::__rep" = type { %union.anon }
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%union.anon = type { %"struct.std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::__long" }
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%"struct.std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::__long" = type { i32, i32, i8* }
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@.str = private unnamed_addr constant [12 x i8] c"some_string\00", align 1
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define void @_Z4foo1c(i8 signext %a) personality i8* bitcast (i32 (...)* @__gxx_personality_sj0 to i8*) {
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entry:
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%s1 = alloca %"class.std::__1::basic_string", align 4
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call void @_ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEE6__initEPKcm(%"class.std::__1::basic_string"* %s1, i8* getelementptr inbounds ([12 x i8], [12 x i8]* @.str, i32 0, i32 0), i32 11)
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%call.i.i.i14.i.i = invoke noalias i8* @_Znwm(i32 1024)
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to label %do.body.i.i.i unwind label %lpad.body
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do.body.i.i.i: ; preds = %entry, %_ZNSt3__116allocator_traitsINS_9allocatorIcEEE9constructIccEEvRS2_PT_RKT0_.exit.i.i.i
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%lsr.iv = phi i32 [ %lsr.iv.next, %_ZNSt3__116allocator_traitsINS_9allocatorIcEEE9constructIccEEvRS2_PT_RKT0_.exit.i.i.i ], [ -1024, %entry ]
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%0 = phi i8* [ %incdec.ptr.i.i.i, %_ZNSt3__116allocator_traitsINS_9allocatorIcEEE9constructIccEEvRS2_PT_RKT0_.exit.i.i.i ], [ %call.i.i.i14.i.i, %entry ]
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%new.isnull.i.i.i.i = icmp eq i8* %0, null
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br i1 %new.isnull.i.i.i.i, label %_ZNSt3__116allocator_traitsINS_9allocatorIcEEE9constructIccEEvRS2_PT_RKT0_.exit.i.i.i, label %new.notnull.i.i.i.i
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new.notnull.i.i.i.i: ; preds = %do.body.i.i.i
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store i8 %a, i8* %0, align 1
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br label %_ZNSt3__116allocator_traitsINS_9allocatorIcEEE9constructIccEEvRS2_PT_RKT0_.exit.i.i.i
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_ZNSt3__116allocator_traitsINS_9allocatorIcEEE9constructIccEEvRS2_PT_RKT0_.exit.i.i.i: ; preds = %new.notnull.i.i.i.i, %do.body.i.i.i
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%1 = phi i8* [ null, %do.body.i.i.i ], [ %0, %new.notnull.i.i.i.i ]
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%incdec.ptr.i.i.i = getelementptr inbounds i8, i8* %1, i32 1
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%lsr.iv.next = add i32 %lsr.iv, 1
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%cmp.i16.i.i = icmp eq i32 %lsr.iv.next, 0
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br i1 %cmp.i16.i.i, label %invoke.cont, label %do.body.i.i.i
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invoke.cont: ; preds = %_ZNSt3__116allocator_traitsINS_9allocatorIcEEE9constructIccEEvRS2_PT_RKT0_.exit.i.i.i
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invoke void @_Z4foo2Pci(i8* %call.i.i.i14.i.i, i32 1024)
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to label %invoke.cont5 unwind label %lpad2
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invoke.cont5: ; preds = %invoke.cont
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%cmp.i.i.i15 = icmp eq i8* %call.i.i.i14.i.i, null
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br i1 %cmp.i.i.i15, label %invoke.cont6, label %_ZNSt3__113__vector_baseIcNS_9allocatorIcEEE5clearEv.exit.i.i.i19
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_ZNSt3__113__vector_baseIcNS_9allocatorIcEEE5clearEv.exit.i.i.i19: ; preds = %invoke.cont5
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call void @_ZdlPv(i8* %call.i.i.i14.i.i)
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br label %invoke.cont6
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invoke.cont6: ; preds = %_ZNSt3__113__vector_baseIcNS_9allocatorIcEEE5clearEv.exit.i.i.i19, %invoke.cont5
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%call10 = call %"class.std::__1::basic_string"* @_ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEED1Ev(%"class.std::__1::basic_string"* %s1)
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ret void
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lpad.body: ; preds = %entry
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%2 = landingpad { i8*, i32 }
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cleanup
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%3 = extractvalue { i8*, i32 } %2, 0
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%4 = extractvalue { i8*, i32 } %2, 1
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br label %ehcleanup
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lpad2: ; preds = %invoke.cont
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%5 = landingpad { i8*, i32 }
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cleanup
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%6 = extractvalue { i8*, i32 } %5, 0
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%7 = extractvalue { i8*, i32 } %5, 1
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%cmp.i.i.i21 = icmp eq i8* %call.i.i.i14.i.i, null
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br i1 %cmp.i.i.i21, label %ehcleanup, label %_ZNSt3__113__vector_baseIcNS_9allocatorIcEEE5clearEv.exit.i.i.i26
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_ZNSt3__113__vector_baseIcNS_9allocatorIcEEE5clearEv.exit.i.i.i26: ; preds = %lpad2
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call void @_ZdlPv(i8* %call.i.i.i14.i.i)
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br label %ehcleanup
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ehcleanup: ; preds = %_ZNSt3__113__vector_baseIcNS_9allocatorIcEEE5clearEv.exit.i.i.i26, %lpad2, %lpad.body
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%exn.slot.0 = phi i8* [ %3, %lpad.body ], [ %6, %lpad2 ], [ %6, %_ZNSt3__113__vector_baseIcNS_9allocatorIcEEE5clearEv.exit.i.i.i26 ]
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%ehselector.slot.0 = phi i32 [ %4, %lpad.body ], [ %7, %lpad2 ], [ %7, %_ZNSt3__113__vector_baseIcNS_9allocatorIcEEE5clearEv.exit.i.i.i26 ]
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%call12 = invoke %"class.std::__1::basic_string"* @_ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEED1Ev(%"class.std::__1::basic_string"* %s1)
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to label %eh.resume unwind label %terminate.lpad
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eh.resume: ; preds = %ehcleanup
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%lpad.val = insertvalue { i8*, i32 } undef, i8* %exn.slot.0, 0
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%lpad.val13 = insertvalue { i8*, i32 } %lpad.val, i32 %ehselector.slot.0, 1
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resume { i8*, i32 } %lpad.val13
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terminate.lpad: ; preds = %ehcleanup
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%8 = landingpad { i8*, i32 }
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catch i8* null
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%9 = extractvalue { i8*, i32 } %8, 0
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call void @__clang_call_terminate(i8* %9)
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unreachable
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}
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declare void @_Z4foo2Pci(i8*, i32)
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define linkonce_odr hidden void @__clang_call_terminate(i8*) {
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%2 = tail call i8* @__cxa_begin_catch(i8* %0)
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tail call void @_ZSt9terminatev()
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unreachable
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}
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declare i8* @__cxa_begin_catch(i8*)
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declare void @_ZSt9terminatev()
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declare %"class.std::__1::basic_string"* @_ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEED1Ev(%"class.std::__1::basic_string"* returned)
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declare void @_ZdlPv(i8*) #3
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declare noalias i8* @_Znwm(i32)
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declare void @_ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEE6__initEPKcm(%"class.std::__1::basic_string"*, i8*, i32)
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declare void @_Unwind_SjLj_Register({ i8*, i32, [4 x i32], i8*, i8*, [5 x i8*] }*)
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declare void @_Unwind_SjLj_Unregister({ i8*, i32, [4 x i32], i8*, i8*, [5 x i8*] }*)
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declare i8* @llvm.frameaddress(i32)
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declare i8* @llvm.stacksave()
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declare void @llvm.stackrestore(i8*)
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declare i32 @llvm.eh.sjlj.setjmp(i8*)
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declare i8* @llvm.eh.sjlj.lsda()
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declare void @llvm.eh.sjlj.callsite(i32)
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declare void @llvm.eh.sjlj.functioncontext(i8*)
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