[llvm] r283091 - [CodeGen] Adding a test showing the current state of poor code gen of

[Alexey Bataev via llvm-commits]

Author: abataev
Date: Mon Oct  3 02:47:01 2016
New Revision: 283091

URL: http://llvm.org/viewvc/llvm-project?rev=283091&view=rev
Log:
[CodeGen] Adding a test showing the current state of poor code gen of
search loop, by Andrey Tischenko

PR27136 shows failure to hoist constant out of loop. This test is used
as start point to fix the failure: it shows the current state of codegen
and discovers what should be fixed

Differential Revision: https://reviews.llvm.org/D25097

Added:
    llvm/trunk/test/CodeGen/X86/loop-search.ll

Added: llvm/trunk/test/CodeGen/X86/loop-search.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/loop-search.ll?rev=283091&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/loop-search.ll (added)
+++ llvm/trunk/test/CodeGen/X86/loop-search.ll Mon Oct  3 02:47:01 2016
@@ -0,0 +1,67 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-apple-darwin | FileCheck %s
+
+; This test comes from PR27136
+; We should hoist loop constant invariant
+
+define zeroext i1 @search(i32 %needle, i32* nocapture readonly %haystack, i32 %count) {
+; CHECK-LABEL: search:
+; CHECK:       ## BB#0: ## %entry
+; CHECK-NEXT:    testl %edx, %edx
+; CHECK-NEXT:    jle LBB0_1
+; CHECK-NEXT:  ## BB#4: ## %for.body.preheader
+; CHECK-NEXT:    movslq %edx, %rcx
+; CHECK-NEXT:    xorl %edx, %edx
+; CHECK-NEXT:    .p2align 4, 0x90
+; CHECK-NEXT:  LBB0_5: ## %for.body
+; CHECK-NEXT:    ## =>This Inner Loop Header: Depth=1
+;            ### FIXME: This loop invariant should be hoisted
+; CHECK-NEXT:    movb $1, %al
+; CHECK-NEXT:    cmpl %edi, (%rsi,%rdx,4)
+; CHECK-NEXT:    je LBB0_6
+; CHECK-NEXT:  ## BB#2: ## %for.cond
+; CHECK-NEXT:    ## in Loop: Header=BB0_5 Depth=1
+; CHECK-NEXT:    incq %rdx
+; CHECK-NEXT:    cmpq %rcx, %rdx
+; CHECK-NEXT:    jl LBB0_5
+;            ### FIXME: BB#3 and LBB0_1 should be merged
+; CHECK-NEXT:  ## BB#3:
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    ## kill: %AL<def> %AL<kill> %EAX<kill>
+; CHECK-NEXT:    retq
+; CHECK-NEXT:  LBB0_1:
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    ## kill: %AL<def> %AL<kill> %EAX<kill>
+; CHECK-NEXT:    retq
+; CHECK-NEXT:  LBB0_6: ## %cleanup
+; CHECK-NEXT:    ## kill: %AL<def> %AL<kill> %EAX<kill>
+; CHECK-NEXT:    retq
+;
+entry:
+  %cmp5 = icmp sgt i32 %count, 0
+  br i1 %cmp5, label %for.body.preheader, label %cleanup
+
+for.body.preheader:                               ; preds = %entry
+  %0 = sext i32 %count to i64
+  br label %for.body
+
+for.cond:                                         ; preds = %for.body
+  %cmp = icmp slt i64 %indvars.iv.next, %0
+  br i1 %cmp, label %for.body, label %cleanup.loopexit
+
+for.body:                                         ; preds = %for.body.preheader, %for.cond
+  %indvars.iv = phi i64 [ 0, %for.body.preheader ], [ %indvars.iv.next, %for.cond ]
+  %arrayidx = getelementptr inbounds i32, i32* %haystack, i64 %indvars.iv
+  %1 = load i32, i32* %arrayidx, align 4
+  %cmp1 = icmp eq i32 %1, %needle
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  br i1 %cmp1, label %cleanup.loopexit, label %for.cond
+
+cleanup.loopexit:                                 ; preds = %for.cond, %for.body
+  %.ph = phi i1 [ false, %for.cond ], [ true, %for.body ]
+  br label %cleanup
+
+cleanup:                                          ; preds = %cleanup.loopexit, %entry
+  %2 = phi i1 [ false, %entry ], [ %.ph, %cleanup.loopexit ]
+  ret i1 %2
+}