From 48cd5b72b13c1283eedb0f3fac7c14167da7fc2f Mon Sep 17 00:00:00 2001
From: Arthur Eubanks <aeubanks@google.com>
Date: Thu, 13 Aug 2020 21:05:03 -0700
Subject: [PATCH] Revert "[SLC] sprintf(dst, "%s", str) -> strcpy(dst, str)"

This reverts commit ab9fc8bae805c785066779e76e7846aabad5609e.

Incorrect transformation if the result is used.
Causes breakages, e.g.
http://green.lab.llvm.org/green/job/test-suite-verify-machineinstrs-x86_64-O3/8193/
---
 llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp     | 14 ++++++++++++--
 .../InstCombine/2010-05-30-memcpy-Struct.ll        |  9 ++-------
 llvm/test/Transforms/InstCombine/sprintf-1.ll      | 10 +++++++---
 3 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index b5f0f56029a4..2f6e60fc09c4 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -2487,11 +2487,21 @@ Value *LibCallSimplifier::optimizeSPrintFString(CallInst *CI,
   }
 
   if (FormatStr[1] == 's') {
-    // sprintf(dest, "%s", str) -> strcpy(dest, str)
+    // sprintf(dest, "%s", str) -> llvm.memcpy(align 1 dest, align 1 str,
+    // strlen(str)+1)
     if (!CI->getArgOperand(2)->getType()->isPointerTy())
       return nullptr;
 
-    return emitStrCpy(CI->getArgOperand(0), CI->getArgOperand(2), B, TLI);
+    Value *Len = emitStrLen(CI->getArgOperand(2), B, DL, TLI);
+    if (!Len)
+      return nullptr;
+    Value *IncLen =
+        B.CreateAdd(Len, ConstantInt::get(Len->getType(), 1), "leninc");
+    B.CreateMemCpy(CI->getArgOperand(0), Align(1), CI->getArgOperand(2),
+                   Align(1), IncLen);
+
+    // The sprintf result is the unincremented number of bytes in the string.
+    return B.CreateIntCast(Len, CI->getType(), false);
   }
   return nullptr;
 }
diff --git a/llvm/test/Transforms/InstCombine/2010-05-30-memcpy-Struct.ll b/llvm/test/Transforms/InstCombine/2010-05-30-memcpy-Struct.ll
index e3cf763917a0..51610698c244 100644
--- a/llvm/test/Transforms/InstCombine/2010-05-30-memcpy-Struct.ll
+++ b/llvm/test/Transforms/InstCombine/2010-05-30-memcpy-Struct.ll
@@ -1,4 +1,3 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt -instcombine -S < %s | FileCheck %s
 ; PR7265
 
@@ -10,14 +9,10 @@ target triple = "x86_64-unknown-linux-gnu"
 @.str = private constant [3 x i8] c"%s\00"
 
 define void @CopyEventArg(%union.anon* %ev) nounwind {
-; CHECK-LABEL: @CopyEventArg(
-; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[CSTR:%.*]] = bitcast %union.anon* [[EV:%.*]] to i8*
-; CHECK-NEXT:    [[STRCPY:%.*]] = call i8* @strcpy(i8* nonnull dereferenceable(1) undef, i8* nonnull dereferenceable(1) [[CSTR]])
-; CHECK-NEXT:    ret void
-;
 entry:
   %call = call i32 (i8*, i8*, ...) @sprintf(i8* undef, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), %union.anon* %ev) nounwind
+; CHECK: bitcast %union.anon* %ev to i8*
+; CHECK: call void @llvm.memcpy.p0i8.p0i8.i64
   ret void
 }
 
diff --git a/llvm/test/Transforms/InstCombine/sprintf-1.ll b/llvm/test/Transforms/InstCombine/sprintf-1.ll
index 77c2d4bbd9b6..9dbfecaecb31 100644
--- a/llvm/test/Transforms/InstCombine/sprintf-1.ll
+++ b/llvm/test/Transforms/InstCombine/sprintf-1.ll
@@ -81,15 +81,19 @@ define void @test_simplify4(i8* %dst) {
   ret void
 }
 
-; Check sprintf(dst, "%s", str) -> strcpy(dst, str)
+; Check sprintf(dst, "%s", str) -> llvm.memcpy(dest, str, strlen(str) + 1, 1).
 
 define void @test_simplify5(i8* %dst, i8* %str) {
 ; CHECK-LABEL: @test_simplify5(
-; CHECK-NEXT:    [[STRCPY:%.*]] = call i8* @strcpy(i8* nonnull dereferenceable(1) [[DST:%.*]], i8* nonnull dereferenceable(1) [[STR:%.*]])
+; CHECK-NEXT:    [[STRLEN:%.*]] = call i32 @strlen(i8* nonnull dereferenceable(1) [[STR:%.*]])
+; CHECK-NEXT:    [[LENINC:%.*]] = add i32 [[STRLEN]], 1
+; CHECK-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 1 [[DST:%.*]], i8* align 1 [[STR]], i32 [[LENINC]], i1 false)
 ; CHECK-NEXT:    ret void
 ;
 ; CHECK-IPRINTF-LABEL: @test_simplify5(
-; CHECK-IPRINTF-NEXT:    [[STRCPY:%.*]] = call i8* @strcpy(i8* nonnull dereferenceable(1) [[DST:%.*]], i8* nonnull dereferenceable(1) [[STR:%.*]])
+; CHECK-IPRINTF-NEXT:    [[STRLEN:%.*]] = call i32 @strlen(i8* nonnull dereferenceable(1) [[STR:%.*]])
+; CHECK-IPRINTF-NEXT:    [[LENINC:%.*]] = add i32 [[STRLEN]], 1
+; CHECK-IPRINTF-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 1 [[DST:%.*]], i8* align 1 [[STR]], i32 [[LENINC]], i1 false)
 ; CHECK-IPRINTF-NEXT:    ret void
 ;
   %fmt = getelementptr [3 x i8], [3 x i8]* @percent_s, i32 0, i32 0