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Clear kill flags in tail duplication. 

If we duplicate an instruction then we must also clear kill flags on any uses we rewrite.
Otherwise we might be killing a register which was used in other BBs.

For example, here the entry BB ended up with these instructions, the ADD having been tail duplicated.

	%vreg24<def> = t2ADDri %vreg10<kill>, 1, pred:14, pred:%noreg, opt:%noreg; GPRnopc:%vreg24 rGPR:%vreg10
	%vreg22<def> = COPY %vreg10; GPR:%vreg22 rGPR:%vreg10

	The copy here is inserted after the add and so needs vreg10 to be live.

llvm-svn: 236782
This commit is contained in:
Pete Cooper 2015-05-07 21:48:26 +00:00
parent d6291964fb
commit ba593ad3f3
2 changed files with 57 additions and 0 deletions
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3
llvm/lib/CodeGen/TailDuplication.cpp
View File

@ -449,6 +449,9 @@ void TailDuplicatePass::DuplicateInstruction(MachineInstr *MI,
DenseMap<unsigned, unsigned>::iterator VI = LocalVRMap.find(Reg); DenseMap<unsigned, unsigned>::iterator VI = LocalVRMap.find(Reg);
if (VI != LocalVRMap.end()) { if (VI != LocalVRMap.end()) {
MO.setReg(VI->second); MO.setReg(VI->second);
// Clear any kill flags from this operand. The new register could have
// uses after this one, so kills are not valid here.
MO.setIsKill(false);
MRI->constrainRegClass(VI->second, MRI->getRegClass(Reg)); MRI->constrainRegClass(VI->second, MRI->getRegClass(Reg));
} }
} }

54
llvm/test/CodeGen/ARM/tail-dup-kill-flags.ll Normal file
View File

@ -0,0 +1,54 @@
; RUN: llc %s -o - -fast-isel=true -O1 -verify-machineinstrs | FileCheck %s
target datalayout = "e-m:o-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"
target triple = "thumbv7-apple-ios8.0.0"
; Tail duplication was incorrectly leaving kill flags on the duplicated instructions.
; The machine verifier is able to spot this error, so this test should pass if it passes verification.
; CHECK-LABEL: @test
%struct.cdiff_ctx = type { i8*, %struct.cdiff_node*, %struct.cdiff_node*, %struct.cdiff_node*, %struct.cdiff_node* }
%struct.cdiff_node = type { i32, i8*, i8*, %struct.cdiff_node* }
declare i32 @logg(i32)
define hidden i32 @test(%struct.cdiff_ctx* nocapture %ctx, %struct.cdiff_node* %tmp10) {
bb:
br label %.outer
bb33: ; preds = %bb92, %.outer
%lines.0 = phi i32 [ %tmp37, %bb92 ], [ %lines.0.ph, %.outer ]
%tmp37 = add i32 %lines.0, 1
%tmp39 = load i32, i32* %tmp57, align 4
%tmp40 = icmp eq i32 %tmp39, %tmp37
br i1 %tmp40, label %bb41, label %bb92
bb41: ; preds = %bb33
%tmp45 = call i32 @strncmp()
%tmp46 = icmp eq i32 %tmp45, 0
br i1 %tmp46, label %bb53, label %bb47
bb47: ; preds = %bb41
%tmp52 = call i32 @logg(i32 %tmp37)
ret i32 -1
bb53: ; preds = %bb41
%tmp54 = getelementptr inbounds %struct.cdiff_node, %struct.cdiff_node* %del.0.ph, i32 0, i32 3
%tmp55 = load %struct.cdiff_node*, %struct.cdiff_node** %tmp54, align 4
br label %.outer
.outer: ; preds = %bb53, %bb
%del.0.ph = phi %struct.cdiff_node* [ %tmp55, %bb53 ], [ null, %bb ]
%lines.0.ph = phi i32 [ 1, %bb53 ], [ 0, %bb ]
%tmp57 = getelementptr inbounds %struct.cdiff_node, %struct.cdiff_node* %del.0.ph, i32 0, i32 0
br label %bb33
bb92: ; preds = %bb33
%tmp93 = call i32 @puts()
br label %bb33
}
declare i32 @strncmp()
declare i32 @puts()