From d02be24cadbba4754df2f3e83473b72c5de698dd Mon Sep 17 00:00:00 2001
From: Daniel Dunbar <daniel@zuster.org>
Date: Sat, 12 Feb 2011 18:19:57 +0000
Subject: [PATCH] SimplifyLibCalls: Add missing legalize check on various
 printf to puts and putchar transforms, their return values are not
 compatible.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125442 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/SimplifyLibCalls.cpp | 14 +++++++----
 test/Transforms/SimplifyLibCalls/Printf.ll | 27 ++++++++++++++++------
 2 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
index c8c00987cc3..ec45b71dd36 100644
--- a/lib/Transforms/Scalar/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
@@ -1092,8 +1092,13 @@ struct PrintFOpt : public LibCallOptimization {
       return CI->use_empty() ? (Value*)CI :
                                ConstantInt::get(CI->getType(), 0);
 
-    // printf("x") -> putchar('x'), even for '%'.  Return the result of putchar
-    // in case there is an error writing to stdout.
+    // Do not do any of the following transformations if the printf return value
+    // is used, in general the printf return value is not compatible with either
+    // putchar() or puts().
+    if (!CI->use_empty())
+      return 0;
+
+    // printf("x") -> putchar('x'), even for '%'.
     if (FormatStr.size() == 1) {
       Value *Res = EmitPutChar(B.getInt32(FormatStr[0]), B, TD);
       if (CI->use_empty()) return CI;
@@ -1126,8 +1131,7 @@ struct PrintFOpt : public LibCallOptimization {
 
     // printf("%s\n", str) --> puts(str)
     if (FormatStr == "%s\n" && CI->getNumArgOperands() > 1 &&
-        CI->getArgOperand(1)->getType()->isPointerTy() &&
-        CI->use_empty()) {
+        CI->getArgOperand(1)->getType()->isPointerTy()) {
       EmitPutS(CI->getArgOperand(1), B, TD);
       return CI;
     }
@@ -1344,7 +1348,7 @@ struct PutsOpt : public LibCallOptimization {
     if (!GetConstantStringInfo(CI->getArgOperand(0), Str))
       return 0;
 
-    if (Str.empty()) {
+    if (Str.empty() && CI->use_empty()) {
       // puts("") -> putchar('\n')
       Value *Res = EmitPutChar(B.getInt32('\n'), B, TD);
       if (CI->use_empty()) return CI;
diff --git a/test/Transforms/SimplifyLibCalls/Printf.ll b/test/Transforms/SimplifyLibCalls/Printf.ll
index d68928ee6b5..caea311ba14 100644
--- a/test/Transforms/SimplifyLibCalls/Printf.ll
+++ b/test/Transforms/SimplifyLibCalls/Printf.ll
@@ -1,23 +1,36 @@
 ; RUN: opt < %s -simplify-libcalls -S -o %t
 ; RUN: FileCheck < %t %s
 
-; CHECK-NOT: call{{.*}}printf
-; CHECK: putchar
-
 @str = internal constant [13 x i8] c"hello world\0A\00"         ; <[13 x i8]*> [#uses=1]
 @str1 = internal constant [2 x i8] c"h\00"              ; <[2 x i8]*> [#uses=1]
 
-define void @foo() {
+declare i32 @printf(i8*, ...)
+
+; CHECK: define void @f0
+; CHECK-NOT: printf
+; CHECK: }
+define void @f0() {
 entry:
         %tmp1 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([13 x i8]* @str, i32 0, i32 0) )         ; <i32> [#uses=0]
         ret void
 }
 
-declare i32 @printf(i8*, ...)
-
-define void @bar() {
+; CHECK: define void @f1
+; CHECK-NOT: printf
+; CHECK: }
+define void @f1() {
 entry:
         %tmp1 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([2 x i8]* @str1, i32 0, i32 0) )         ; <i32> [#uses=0]
         ret void
 }
 
+; Verify that we don't turn this into a putchar call (thus changing the return
+; value).
+;
+; CHECK: define i32 @f2
+; CHECK: printf
+; CHECK: }
+define i32 @f2() {
+  %call = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([2 x i8]* @str1, i32 0, i32 0))
+  ret i32 %call
+}
-- 
2.34.1