[PeepholeOptimizer] Don't assume bitcast def always has input
Summary:
If we have a MI marked with bitcast bits, but without input operands,
PeepholeOptimizer might crash with assert.
eg:
If we apply the changes in PPCInstrVSX.td as in this patch:
[(set v4i32:$XT, (bitconvert (v16i8 immAllOnesV)))]>;
We will get assert in PeepholeOptimizer.
```
llvm-lit llvm-project/llvm/test/CodeGen/PowerPC/build-vector-tests.ll -v
llvm-project/llvm/include/llvm/CodeGen/MachineInstr.h:417: const
llvm::MachineOperand &llvm::MachineInstr::getOperand(unsigned int)
const: Assertion `i < getNumOperands() && "getOperand() out of range!"'
failed.
```
The fix is to abort if we found out of bound access.
Reviewers: qcolombet, MatzeB, hfinkel, arsenm
Reviewed By: qcolombet
Subscribers: wdng, arsenm, steven.zhang, wuzish, nemanjai, hiraditya, kbarton, MaskRay, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65542
llvm-svn: 369261
diff --git a/llvm/lib/CodeGen/PeepholeOptimizer.cpp b/llvm/lib/CodeGen/PeepholeOptimizer.cpp
index e613d07..6818195 100644
--- a/llvm/lib/CodeGen/PeepholeOptimizer.cpp
+++ b/llvm/lib/CodeGen/PeepholeOptimizer.cpp
@@ -1853,6 +1853,11 @@
SrcIdx = OpIdx;
}
+ // In some rare case, Def has no input, SrcIdx is out of bound,
+ // getOperand(SrcIdx) will fail below.
+ if (SrcIdx >= Def->getNumOperands())
+ return ValueTrackerResult();
+
// Stop when any user of the bitcast is a SUBREG_TO_REG, replacing with a COPY
// will break the assumed guarantees for the upper bits.
for (const MachineInstr &UseMI : MRI.use_nodbg_instructions(DefOp.getReg())) {
diff --git a/llvm/lib/Target/PowerPC/PPCInstrVSX.td b/llvm/lib/Target/PowerPC/PPCInstrVSX.td
index 787545c..dec4c32 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrVSX.td
+++ b/llvm/lib/Target/PowerPC/PPCInstrVSX.td
@@ -1314,7 +1314,7 @@
isReMaterializable = 1 in {
def XXLEQVOnes : XX3Form_SameOp<60, 186, (outs vsrc:$XT), (ins),
"xxleqv $XT, $XT, $XT", IIC_VecGeneral,
- [(set v4i32:$XT, (v4i32 immAllOnesV))]>;
+ [(set v4i32:$XT, (bitconvert (v16i8 immAllOnesV)))]>;
}
def XXLORC : XX3Form<60, 170,
@@ -4103,8 +4103,6 @@
}
let Predicates = [HasP8Vector] in {
- def : Pat<(v4i32 (bitconvert (v16i8 immAllOnesV))),
- (XXLEQVOnes)>;
def : Pat<(v1i128 (bitconvert (v16i8 immAllOnesV))),
(v1i128 (COPY_TO_REGCLASS(XXLEQVOnes), VSRC))>;
def : Pat<(v2i64 (bitconvert (v16i8 immAllOnesV))),
diff --git a/llvm/test/CodeGen/PowerPC/bitcast-peephole.mir b/llvm/test/CodeGen/PowerPC/bitcast-peephole.mir
new file mode 100644
index 0000000..1523857
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/bitcast-peephole.mir
@@ -0,0 +1,23 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=powerpc64le-linux-gnu -run-pass=peephole-opt -verify-machineinstrs -o - %s | FileCheck %s
+
+---
+name: bitCast
+tracksRegLiveness: true
+body: |
+ bb.0.entry:
+ ; CHECK-LABEL: name: bitCast
+ ; CHECK: [[XXLEQVOnes:%[0-9]+]]:vsrc = XXLEQVOnes
+ ; CHECK: $v2 = COPY [[XXLEQVOnes]]
+ ; CHECK: BLR8 implicit $lr8, implicit $rm, implicit $v2
+ %0:vsrc = XXLEQVOnes
+ $v2 = COPY %0
+ BLR8 implicit $lr8, implicit $rm, implicit $v2
+
+...
+
+# This used to hit an assertion:
+# llvm/include/llvm/CodeGen/MachineInstr.h:417: const
+# llvm::MachineOperand &llvm::MachineInstr::getOperand(unsigned int)
+# const: Assertion `i < getNumOperands() && "getOperand() out of range!"' failed.
+#