[PATCH] D38734: [MachineCombiner] Fix initialisation of LastUpdate for incremental update.
Paul Walker via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Oct 11 02:56:42 PDT 2017
paulwalker-arm updated this revision to Diff 118574.
paulwalker-arm added a comment.
As requested I've simplified the patch's mir test.
https://reviews.llvm.org/D38734
Files:
lib/CodeGen/MachineCombiner.cpp
test/CodeGen/AArch64/machine-combiner.mir
Index: test/CodeGen/AArch64/machine-combiner.mir
===================================================================
--- /dev/null
+++ test/CodeGen/AArch64/machine-combiner.mir
@@ -0,0 +1,48 @@
+# RUN: llc -mtriple=aarch64-none-linux-gnu -mcpu=cortex-a57 -enable-unsafe-fp-math \
+# RUN: -run-pass machine-combiner -machine-combiner-inc-threshold=0 \
+# RUN: -verify-machineinstrs -o - %s | FileCheck %s
+---
+# Test incremental depth updates succeed when triggered after the removal of
+# the first instruction in a basic block.
+
+# CHECK-LABEL: name: inc_update_iterator_test
+name: inc_update_iterator_test
+registers:
+ - { id: 0, class: fpr64 }
+ - { id: 1, class: gpr32 }
+ - { id: 2, class: gpr32 }
+ - { id: 3, class: gpr32 }
+ - { id: 4, class: gpr32 }
+ - { id: 5, class: gpr32 }
+ - { id: 6, class: gpr32 }
+ - { id: 7, class: fpr64 }
+ - { id: 8, class: fpr64 }
+ - { id: 9, class: fpr64 }
+body: |
+ bb.0:
+ successors: %bb.1, %bb.2
+
+ %3 = COPY %w2
+ %2 = COPY %w1
+ %1 = COPY %w0
+ %0 = COPY %d0
+ %4 = SUBSWrr %1, %2, implicit-def %nzcv
+ Bcc 13, %bb.2, implicit %nzcv
+ B %bb.1
+
+ bb.1:
+ ; CHECK: MADDWrrr %1, %2, %3
+ %5 = MADDWrrr %1, %2, %wzr
+ %6 = ADDWrr %3, killed %5
+ %7 = SCVTFUWDri killed %6
+ ; CHECK: FMADDDrrr %7, %7, %0
+ %8 = FMULDrr %7, %7
+ %9 = FADDDrr %0, killed %8
+ %d0 = COPY %9
+ RET_ReallyLR implicit %d0
+
+ bb.2:
+ %d0 = COPY %0
+ RET_ReallyLR implicit %d0
+
+...
Index: lib/CodeGen/MachineCombiner.cpp
===================================================================
--- lib/CodeGen/MachineCombiner.cpp
+++ lib/CodeGen/MachineCombiner.cpp
@@ -415,7 +415,7 @@
bool IncrementalUpdate = false;
auto BlockIter = MBB->begin();
- auto LastUpdate = BlockIter;
+ decltype(BlockIter) LastUpdate;
// Check if the block is in a loop.
const MachineLoop *ML = MLI->getLoopFor(MBB);
if (!MinInstr)
@@ -503,9 +503,11 @@
InstrIdxForVirtReg, P,
!IncrementalUpdate) &&
preservesResourceLen(MBB, BlockTrace, InsInstrs, DelInstrs)) {
- if (MBB->size() > inc_threshold)
+ if (MBB->size() > inc_threshold) {
// Use incremental depth updates for basic blocks above treshold
IncrementalUpdate = true;
+ LastUpdate = BlockIter;
+ }
insertDeleteInstructions(MBB, MI, InsInstrs, DelInstrs, MinInstr,
RegUnits, IncrementalUpdate);
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