[PATCH] D121883: [BPF] Fix a bug in BPFAdjustOpt pass for icmp transformation

[Yonghong Song via Phabricator via llvm-commits]

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When checking a bcc issue related to bcc tool inject.py,
I found a bug in BPFAdjustOpt pass for icmp transformation,
caused by typo's. For the following condition:

  Cond2Op != ICmpInst::ICMP_SLT && Cond1Op != ICmpInst::ICMP_SLE

it should be

  Cond2Op != ICmpInst::ICMP_SLT && Cond2Op != ICmpInst::ICMP_SLE

The problem is then fixed and a test case is added.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D121883

Files:
  llvm/lib/Target/BPF/BPFAdjustOpt.cpp
  llvm/test/CodeGen/BPF/adjust-opt-icmp5.ll


Index: llvm/test/CodeGen/BPF/adjust-opt-icmp5.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/BPF/adjust-opt-icmp5.ll
@@ -0,0 +1,71 @@
+; RUN: opt -O2 -S -mtriple=bpf-pc-linux %s -o %t1
+; RUN: llc %t1 -o - | FileCheck -check-prefixes=CHECK,CHECK-V1 %s
+; RUN: opt -O2 -S -mtriple=bpf-pc-linux %s -o %t1
+; RUN: llc %t1 -mcpu=v3 -o - | FileCheck -check-prefixes=CHECK,CHECK-V3 %s
+;
+; Source:
+;   int bar(int);
+;   int test(int *p) {
+;     if (*p <= 0 || *p >= 7)
+;       return 0;
+;     return bar(*p);
+;   }
+; Compilation flag:
+;   clang -target bpf -O2 -S -emit-llvm -Xclang -disable-llvm-passes test.c
+
+; Function Attrs: nounwind
+define dso_local i32 @test(i32* noundef %p) #0 {
+entry:
+  %retval = alloca i32, align 4
+  %p.addr = alloca i32*, align 8
+  store i32* %p, i32** %p.addr, align 8, !tbaa !3
+  %0 = load i32*, i32** %p.addr, align 8, !tbaa !3
+  %1 = load i32, i32* %0, align 4, !tbaa !7
+  %cmp = icmp sle i32 %1, 0
+  br i1 %cmp, label %if.then, label %lor.lhs.false
+
+lor.lhs.false:                                    ; preds = %entry
+  %2 = load i32*, i32** %p.addr, align 8, !tbaa !3
+  %3 = load i32, i32* %2, align 4, !tbaa !7
+  %cmp1 = icmp sge i32 %3, 7
+  br i1 %cmp1, label %if.then, label %if.end
+
+if.then:                                          ; preds = %lor.lhs.false, %entry
+  store i32 0, i32* %retval, align 4
+  br label %return
+
+if.end:                                           ; preds = %lor.lhs.false
+  %4 = load i32*, i32** %p.addr, align 8, !tbaa !3
+  %5 = load i32, i32* %4, align 4, !tbaa !7
+  %call = call i32 @bar(i32 noundef %5)
+  store i32 %call, i32* %retval, align 4
+  br label %return
+
+return:                                           ; preds = %if.end, %if.then
+  %6 = load i32, i32* %retval, align 4
+  ret i32 %6
+}
+
+; CHECK-LABEL: test
+; CHECK-V1:    if r[[#]] s> r[[#]] goto
+; CHECK-V1:    if r[[#]] s> 6 goto
+; CHECK-V3:    if w[[#]] s< 1 goto
+; CHECK-V3:    if w[[#]] s> 6 goto
+
+declare dso_local i32 @bar(i32 noundef) #1
+
+attributes #0 = { nounwind "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
+attributes #1 = { "frame-pointer"="all" "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
+
+!llvm.module.flags = !{!0, !1}
+!llvm.ident = !{!2}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 7, !"frame-pointer", i32 2}
+!2 = !{!"clang version 15.0.0 (https://github.com/llvm/llvm-project.git 0d37a76d31c05372908908ff2f01fc58bbf575e8)"}
+!3 = !{!4, !4, i64 0}
+!4 = !{!"any pointer", !5, i64 0}
+!5 = !{!"omnipotent char", !6, i64 0}
+!6 = !{!"Simple C/C++ TBAA"}
+!7 = !{!8, !8, i64 0}
+!8 = !{!"int", !5, i64 0}
Index: llvm/lib/Target/BPF/BPFAdjustOpt.cpp
===================================================================
--- llvm/lib/Target/BPF/BPFAdjustOpt.cpp
+++ llvm/lib/Target/BPF/BPFAdjustOpt.cpp
@@ -259,10 +259,10 @@
     return false;
 
   if (Cond1Op == ICmpInst::ICMP_SGT || Cond1Op == ICmpInst::ICMP_SGE) {
-    if (Cond2Op != ICmpInst::ICMP_SLT && Cond1Op != ICmpInst::ICMP_SLE)
+    if (Cond2Op != ICmpInst::ICMP_SLT && Cond2Op != ICmpInst::ICMP_SLE)
       return false;
   } else if (Cond1Op == ICmpInst::ICMP_SLT || Cond1Op == ICmpInst::ICMP_SLE) {
-    if (Cond2Op != ICmpInst::ICMP_SGT && Cond1Op != ICmpInst::ICMP_SGE)
+    if (Cond2Op != ICmpInst::ICMP_SGT && Cond2Op != ICmpInst::ICMP_SGE)
       return false;
   } else {
     return false;


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