From e5b9a43eaa4482eb668a4b8be7360ae95807cb75 Mon Sep 17 00:00:00 2001
From: Sanjay Patel <spatel@rotateright.com>
Date: Tue, 1 Oct 2019 21:25:36 +0000
Subject: [PATCH] [BypassSlowDivision][CodeGenPrepare] avoid crashing on unused
code (PR43514)
https://bugs.llvm.org/show_bug.cgi?id=43514
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@373394 91177308-0d34-0410-b5e6-96231b3b80d8
---
lib/Transforms/Utils/BypassSlowDivision.cpp | 8 ++++++--
test/CodeGen/X86/bypass-slow-division-64.ll | 10 ++++++++++
2 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/lib/Transforms/Utils/BypassSlowDivision.cpp b/lib/Transforms/Utils/BypassSlowDivision.cpp
index df299f673f6..9a6761040bd 100644
--- a/lib/Transforms/Utils/BypassSlowDivision.cpp
+++ b/lib/Transforms/Utils/BypassSlowDivision.cpp
@@ -448,13 +448,17 @@ bool llvm::bypassSlowDivision(BasicBlock *BB,
DivCacheTy PerBBDivCache;
bool MadeChange = false;
- Instruction* Next = &*BB->begin();
+ Instruction *Next = &*BB->begin();
while (Next != nullptr) {
// We may add instructions immediately after I, but we want to skip over
// them.
- Instruction* I = Next;
+ Instruction *I = Next;
Next = Next->getNextNode();
+ // Ignore dead code to save time and avoid bugs.
+ if (I->hasNUses(0))
+ continue;
+
FastDivInsertionTask Task(I, BypassWidths);
if (Value *Replacement = Task.getReplacement(PerBBDivCache)) {
I->replaceAllUsesWith(Replacement);
diff --git a/test/CodeGen/X86/bypass-slow-division-64.ll b/test/CodeGen/X86/bypass-slow-division-64.ll
index 11fc0df2443..14a71050e94 100644
--- a/test/CodeGen/X86/bypass-slow-division-64.ll
+++ b/test/CodeGen/X86/bypass-slow-division-64.ll
@@ -75,3 +75,13 @@ define i64 @Test_get_quotient_and_remainder(i64 %a, i64 %b) nounwind {
%result = add i64 %resultdiv, %resultrem
ret i64 %result
}
+
+define void @PR43514(i32 %x, i32 %y) {
+; CHECK-LABEL: PR43514:
+; CHECK: # %bb.0:
+; CHECK-NEXT: retq
+ %z1 = zext i32 %x to i64
+ %z2 = zext i32 %y to i64
+ %s = srem i64 %z1, %z2
+ ret void
+}
--
2.40.0