From 011fb5bf8b31316472fccb1a19c91912246df9b2 Mon Sep 17 00:00:00 2001
From: Reid Kleckner <rnk@google.com>
Date: Sat, 28 Mar 2020 11:03:14 -0700
Subject: [PATCH] [CodeGen] Fix sinking local values in lpads with phis
There was already a test case for landingpads to handle this case, but I
had forgotten to consider PHI instructions preceding the EH_LABEL in the
landingpad.
PR45261
---
llvm/lib/CodeGen/SelectionDAG/FastISel.cpp | 17 +++++++++-
llvm/test/CodeGen/X86/sink-local-value.ll | 36 ++++++++++++++++++++++
2 files changed, 52 insertions(+), 1 deletion(-)
diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index 5ac3606dc662..2638b1e8a05c 100644
--- llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -225,6 +225,21 @@ static bool isRegUsedByPhiNodes(unsigned DefReg,
return false;
}
+static bool isTerminatingEHLabel(MachineBasicBlock *MBB, MachineInstr &MI) {
+ // Ignore non-EH labels.
+ if (!MI.isEHLabel())
+ return false;
+
+ // Any EH label outside a landing pad must be for an invoke. Consider it a
+ // terminator.
+ if (!MBB->isEHPad())
+ return true;
+
+ // If this is a landingpad, the first non-phi instruction will be an EH_LABEL.
+ // Don't consider that label to be a terminator.
+ return MI.getIterator() != MBB->getFirstNonPHI();
+}
+
/// Build a map of instruction orders. Return the first terminator and its
/// order. Consider EH_LABEL instructions to be terminators as well, since local
/// values for phis after invokes must be materialized before the call.
@@ -233,7 +248,7 @@ void FastISel::InstOrderMap::initialize(
unsigned Order = 0;
for (MachineInstr &I : *MBB) {
if (!FirstTerminator &&
- (I.isTerminator() || (I.isEHLabel() && &I != &MBB->front()))) {
+ (I.isTerminator() || isTerminatingEHLabel(MBB, I))) {
FirstTerminator = &I;
FirstTerminatorOrder = Order;
}
diff --git a/llvm/test/CodeGen/X86/sink-local-value.ll b/llvm/test/CodeGen/X86/sink-local-value.ll
index b0e511ac1189..f7d861ac9b6c 100644
--- llvm/test/CodeGen/X86/sink-local-value.ll
+++ llvm/test/CodeGen/X86/sink-local-value.ll
@@ -145,6 +145,42 @@ try.cont: ; preds = %entry, %lpad
; CHECK: retl
+define i32 @lpad_phi() personality i32 (...)* @__gxx_personality_v0 {
+entry:
+ store i32 42, i32* @sink_across
+ invoke void @may_throw()
+ to label %try.cont unwind label %lpad
+
+lpad: ; preds = %entry
+ %p = phi i32 [ 11, %entry ] ; Trivial, but -O0 keeps it
+ %0 = landingpad { i8*, i32 }
+ catch i8* null
+ store i32 %p, i32* @sink_across
+ br label %try.cont
+
+try.cont: ; preds = %entry, %lpad
+ %r.0 = phi i32 [ 13, %entry ], [ 55, %lpad ]
+ ret i32 %r.0
+}
+
+; The constant materialization should be *after* the stores to sink_across, but
+; before any EH_LABEL.
+
+; CHECK-LABEL: lpad_phi:
+; CHECK: movl $42, sink_across
+; CHECK: movl $13, %{{[a-z]*}}
+; CHECK: .Ltmp{{.*}}:
+; CHECK: calll may_throw
+; CHECK: .Ltmp{{.*}}:
+; CHECK: jmp .LBB{{.*}}
+; CHECK: .LBB{{.*}}: # %lpad
+; CHECK-NEXT: .Ltmp{{.*}}:
+; CHECK: movl {{.*}}, sink_across
+; CHECK: movl $55, %{{[a-z]*}}
+; CHECK: .LBB{{.*}}: # %try.cont
+; CHECK: retl
+
+
; Function Attrs: nounwind readnone speculatable
declare void @llvm.dbg.value(metadata, metadata, metadata) #0
