From: Evan Cheng Date: Fri, 19 Dec 2008 20:58:01 +0000 (+0000) Subject: Fix PR3149. If an early clobber def is a physical register and it is tied to an input... X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=5379f412bc6ac6171f3bd73930197bfce88c2faa;p=oota-llvm.git Fix PR3149. If an early clobber def is a physical register and it is tied to an input operand, it effectively extends the live range of the physical register. Currently we do not have a good way to represent this. 172 %ECX = MOV32rr %reg1039 180 INLINEASM , 10, %EAX, 14, %ECX, 9, %EAX, 36, , 1, %reg0, 0, 9, %ECX, 36, , 1, %reg0, 0 188 %EAX = MOV32rr %EAX 196 %ECX = MOV32rr %ECX 204 %ECX = MOV32rr %ECX 212 %EAX = MOV32rr %EAX 220 %EAX = MOV32rr %EAX 228 %reg1039 = MOV32rr %ECX The early clobber operand ties ECX input to the ECX def. The live interval of ECX is represented as this: %reg20,inf = [46,47:1)[174,230:0) 0@174-(230) 1@46-(47) The right way to represent this is something like %reg20,inf = [46,47:2)[174,182:1)[181:230:0) 0@174-(182) 1@181-230 @2@46-(47) Of course that won't work since that means overlapping live ranges defined by two val#. The workaround for now is to add a bit to val# which says the val# is redefined by a early clobber def somewhere. This prevents the move at 228 from being optimized away by SimpleRegisterCoalescing::AdjustCopiesBackFrom. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61259 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/include/llvm/CodeGen/LiveInterval.h b/include/llvm/CodeGen/LiveInterval.h index 7ef24897d4b..4062480b260 100644 --- a/include/llvm/CodeGen/LiveInterval.h +++ b/include/llvm/CodeGen/LiveInterval.h @@ -38,16 +38,19 @@ namespace llvm { /// - or reg # of the definition if it's a stack slot liveinterval. /// copy - Copy iff val# is defined by a copy; zero otherwise. /// hasPHIKill - One or more of the kills are PHI nodes. + /// redefByEC - Re-defined by early clobber somewhere during the live range. /// kills - Instruction # of the kills. struct VNInfo { unsigned id; unsigned def; MachineInstr *copy; - bool hasPHIKill; + bool hasPHIKill : 1; + bool redefByEC : 1; SmallVector kills; - VNInfo() : id(~1U), def(~1U), copy(0), hasPHIKill(false) {} + VNInfo() + : id(~1U), def(~1U), copy(0), hasPHIKill(false), redefByEC(false) {} VNInfo(unsigned i, unsigned d, MachineInstr *c) - : id(i), def(d), copy(c), hasPHIKill(false) {} + : id(i), def(d), copy(c), hasPHIKill(false), redefByEC(false) {} }; /// LiveRange structure - This represents a simple register range in the @@ -177,6 +180,7 @@ namespace llvm { DstValNo->def = SrcValNo->def; DstValNo->copy = SrcValNo->copy; DstValNo->hasPHIKill = SrcValNo->hasPHIKill; + DstValNo->redefByEC = SrcValNo->redefByEC; DstValNo->kills = SrcValNo->kills; } diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp index 52b57d6d2ea..1900c1a4d7d 100644 --- a/lib/CodeGen/LiveIntervalAnalysis.cpp +++ b/lib/CodeGen/LiveIntervalAnalysis.cpp @@ -360,6 +360,7 @@ void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock *mbb, mi->getOpcode() == TargetInstrInfo::INSERT_SUBREG || tii_->isMoveInstr(*mi, SrcReg, DstReg)) CopyMI = mi; + // Earlyclobbers move back one. ValNo = interval.getNextValue(defIndex, CopyMI, VNInfoAllocator); assert(ValNo->id == 0 && "First value in interval is not 0?"); @@ -435,9 +436,8 @@ void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock *mbb, assert(interval.containsOneValue()); unsigned DefIndex = getDefIndex(interval.getValNumInfo(0)->def); unsigned RedefIndex = getDefIndex(MIIdx); - // Earlyclobbers move back one. - if (MO.isEarlyClobber()) - RedefIndex = getUseIndex(MIIdx); + // It cannot be an early clobber MO. + assert(!MO.isEarlyClobber() && "Unexpected early clobber!"); const LiveRange *OldLR = interval.getLiveRangeContaining(RedefIndex-1); VNInfo *OldValNo = OldLR->valno; @@ -505,9 +505,8 @@ void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock *mbb, // live until the end of the block. We've already taken care of the // rest of the live range. unsigned defIndex = getDefIndex(MIIdx); - // Earlyclobbers move back one. - if (MO.isEarlyClobber()) - defIndex = getUseIndex(MIIdx); + // It cannot be an early clobber MO. + assert(!MO.isEarlyClobber() && "Unexpected early clobber!"); VNInfo *ValNo; MachineInstr *CopyMI = NULL; @@ -592,8 +591,11 @@ exit: // Already exists? Extend old live interval. LiveInterval::iterator OldLR = interval.FindLiveRangeContaining(start); - VNInfo *ValNo = (OldLR != interval.end()) + bool Extend = OldLR != interval.end(); + VNInfo *ValNo = Extend ? OldLR->valno : interval.getNextValue(start, CopyMI, VNInfoAllocator); + if (MO.isEarlyClobber() && Extend) + ValNo->redefByEC = true; LiveRange LR(start, end, ValNo); interval.addRange(LR); interval.addKill(LR.valno, end); diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp index 41022a6e269..cfac82613ff 100644 --- a/lib/CodeGen/SimpleRegisterCoalescing.cpp +++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp @@ -119,6 +119,26 @@ bool SimpleRegisterCoalescing::AdjustCopiesBackFrom(LiveInterval &IntA, if (ALR == IntA.end()) // Should never happen! return false; VNInfo *AValNo = ALR->valno; + // If it's re-defined by an early clobber somewhere in the live range, then + // it's not safe to eliminate the copy. FIXME: This is a temporary workaround. + // See PR3149: + // 172 %ECX = MOV32rr %reg1039 + // 180 INLINEASM , 10, %EAX, 14, %ECX, 9, %EAX, + // 36, , 1, %reg0, 0, 9, %ECX, 36, , 1, %reg0, 0 + // 188 %EAX = MOV32rr %EAX + // 196 %ECX = MOV32rr %ECX + // 204 %ECX = MOV32rr %ECX + // 212 %EAX = MOV32rr %EAX + // 220 %EAX = MOV32rr %EAX + // 228 %reg1039 = MOV32rr %ECX + // The early clobber operand ties ECX input to the ECX def. + // + // The live interval of ECX is represented as this: + // %reg20,inf = [46,47:1)[174,230:0) 0@174-(230) 1@46-(47) + // The coalescer has no idea there was a def in the middle of [174,230]. + if (AValNo->redefByEC) + return false; // If AValNo is defined as a copy from IntB, we can potentially process this. // Get the instruction that defines this value number. diff --git a/test/CodeGen/PowerPC/2007-04-30-InlineAsmEarlyClobber.ll b/test/CodeGen/PowerPC/2007-04-30-InlineAsmEarlyClobber.ll index 2466f4fc8e9..ba0f8fe1b77 100644 --- a/test/CodeGen/PowerPC/2007-04-30-InlineAsmEarlyClobber.ll +++ b/test/CodeGen/PowerPC/2007-04-30-InlineAsmEarlyClobber.ll @@ -17,7 +17,7 @@ target triple = "powerpc-apple-darwin8.8.0" ; return ((long long)Y << 32) | X; ;} -define i64 @test(i32 %A, i32 %B, i32 %C) { +define i64 @test(i32 %A, i32 %B, i32 %C) nounwind { entry: %Y = alloca i32, align 4 ; [#uses=2] %tmp4 = call i32 asm "subf${3:I}c $1,$4,$3\0A\09subfze $0,$2", "=r,=*&r,r,rI,r"( i32* %Y, i32 %A, i32 %B, i32 %C ) ; [#uses=1] diff --git a/test/CodeGen/X86/2008-12-19-EarlyClobberBug.ll b/test/CodeGen/X86/2008-12-19-EarlyClobberBug.ll new file mode 100644 index 00000000000..6442ac7c765 --- /dev/null +++ b/test/CodeGen/X86/2008-12-19-EarlyClobberBug.ll @@ -0,0 +1,32 @@ +; RUN: llvm-as < %s | llc -mtriple=i386-apple-darwin | %prcontext End 1 | grep {movl.*%ecx} +; PR3149 + +@"\01LC" = internal constant [7 x i8] c"n0=%d\0A\00" ; <[7 x i8]*> [#uses=1] +@llvm.used = appending global [1 x i8*] [ i8* bitcast (i32 (i64, i64)* @umoddi3 to i8*) ], section "llvm.metadata" ; <[1 x i8*]*> [#uses=0] + +define i32 @umoddi3(i64 %u, i64 %v) nounwind noinline { +entry: + %0 = trunc i64 %v to i32 ; [#uses=2] + %1 = trunc i64 %u to i32 ; [#uses=4] + %2 = lshr i64 %u, 32 ; [#uses=1] + %3 = trunc i64 %2 to i32 ; [#uses=2] + %4 = tail call i32 (i8*, ...)* @printf(i8* getelementptr ([7 x i8]* @"\01LC", i32 0, i32 0), i32 %1) nounwind ; [#uses=0] + %5 = icmp ult i32 %1, %0 ; [#uses=1] + br i1 %5, label %bb2, label %bb + +bb: ; preds = %entry + %6 = lshr i64 %v, 32 ; [#uses=1] + %7 = trunc i64 %6 to i32 ; [#uses=1] + %asmtmp = tail call { i32, i32 } asm "subl $5,$1\0A\09sbbl $3,$0", "=r,=&r,0,imr,1,imr,~{dirflag},~{fpsr},~{flags}"(i32 %3, i32 %7, i32 %1, i32 %0) nounwind ; <{ i32, i32 }> [#uses=2] + %asmresult = extractvalue { i32, i32 } %asmtmp, 0 ; [#uses=1] + %asmresult1 = extractvalue { i32, i32 } %asmtmp, 1 ; [#uses=1] + br label %bb2 + +bb2: ; preds = %bb, %entry + %n1.0 = phi i32 [ %asmresult, %bb ], [ %3, %entry ] ; [#uses=1] + %n0.0 = phi i32 [ %asmresult1, %bb ], [ %1, %entry ] ; [#uses=1] + %8 = add i32 %n0.0, %n1.0 ; [#uses=1] + ret i32 %8 +} + +declare i32 @printf(i8*, ...) nounwind