Delete dead PHI machine instructions. These can be created due to type

legalization even when the IR-level optimizer has removed dead phis, such
as when the high half of an i64 value is unused on a 32-bit target.
I had to adjust a few test cases that had dead phis.
This is a partial fix for Radar 7627077.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95816 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bob Wilson 2010-02-10 22:58:57 +00:00
parent b8ff934e94
commit 5e2b05a71e
3 changed files with 7 additions and 5 deletions

View File

@ -55,7 +55,7 @@ FunctionPass *llvm::createDeadMachineInstructionElimPass() {
bool DeadMachineInstructionElim::isDead(const MachineInstr *MI) const {
// Don't delete instructions with side effects.
bool SawStore = false;
if (!MI->isSafeToMove(TII, SawStore, 0))
if (!MI->isSafeToMove(TII, SawStore, 0) && !MI->isPHI())
return false;
// Examine each operand.

View File

@ -32,16 +32,16 @@ bb.i35: ; preds = %bb142
br label %phi1.exit
phi1.exit: ; preds = %bb.i35, %bb142
%.pn = phi double [ %6, %bb.i35 ], [ 0.000000e+00, %bb142 ] ; <double> [#uses=0]
%.pn = phi double [ %6, %bb.i35 ], [ 0.000000e+00, %bb142 ] ; <double> [#uses=1]
%9 = phi double [ %8, %bb.i35 ], [ 0.000000e+00, %bb142 ] ; <double> [#uses=1]
%10 = fmul double undef, %9 ; <double> [#uses=0]
%10 = fmul double %.pn, %9 ; <double> [#uses=1]
br i1 %14, label %phi0.exit, label %bb.i
bb.i: ; preds = %phi1.exit
unreachable
phi0.exit: ; preds = %phi1.exit
%11 = fsub double %4, undef ; <double> [#uses=1]
%11 = fsub double %4, %10 ; <double> [#uses=1]
%12 = fadd double 0.000000e+00, %11 ; <double> [#uses=1]
store double %12, double* undef, align 4
br label %bb142

View File

@ -36,7 +36,9 @@ bb.i6.i: ; preds = %bb.i6.i, %stepsystem.exit.i
bb107.i.i: ; preds = %bb107.i.i, %bb.i6.i
%q_addr.0.i.i.in = phi %struct.bnode** [ null, %bb107.i.i ], [ %4, %bb.i6.i ] ; <%struct.bnode**> [#uses=1]
%q_addr.0.i.i = load %struct.bnode** %q_addr.0.i.i.in ; <%struct.bnode*> [#uses=0]
%q_addr.0.i.i = load %struct.bnode** %q_addr.0.i.i.in ; <%struct.bnode*> [#uses=1]
%q_addr.1 = getelementptr %struct.anon* %0, i32 0, i32 4, i32 1
store %struct.bnode* %q_addr.0.i.i, %struct.bnode** %q_addr.1, align 4
br label %bb107.i.i
bb47.loopexit.i: ; preds = %bb32.i