[llvm] r332106 - [Analysis] Validate the return type of s(n)printf like libcalls

[Martin Storsjo via llvm-commits]

Author: mstorsjo
Date: Fri May 11 09:53:56 2018
New Revision: 332106

URL: http://llvm.org/viewvc/llvm-project?rev=332106&view=rev
Log:
[Analysis] Validate the return type of s(n)printf like libcalls

If the sprintf function is static (as on mingw-w64, where many stdio
functions are static inline wrappers), earlier optimization passes
could optimize out the return value altogether, and make it void,
which could break optimizations of this libcall that touch the
return value.

This fixes the issue discussed in PR37408 for the sprintf function.

Differential Revision: https://reviews.llvm.org/D46752

Added:
    llvm/trunk/test/Transforms/InstCombine/sprintf-void.ll
Modified:
    llvm/trunk/lib/Analysis/TargetLibraryInfo.cpp

Modified: llvm/trunk/lib/Analysis/TargetLibraryInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/TargetLibraryInfo.cpp?rev=332106&r1=332105&r2=332106&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/TargetLibraryInfo.cpp (original)
+++ llvm/trunk/lib/Analysis/TargetLibraryInfo.cpp Fri May 11 09:53:56 2018
@@ -692,10 +692,12 @@ bool TargetLibraryInfoImpl::isValidProto
   case LibFunc_siprintf:
   case LibFunc_sprintf:
     return (NumParams >= 2 && FTy.getParamType(0)->isPointerTy() &&
-            FTy.getParamType(1)->isPointerTy());
+            FTy.getParamType(1)->isPointerTy() &&
+            FTy.getReturnType()->isIntegerTy(32));
   case LibFunc_snprintf:
     return (NumParams == 3 && FTy.getParamType(0)->isPointerTy() &&
-            FTy.getParamType(2)->isPointerTy());
+            FTy.getParamType(2)->isPointerTy() &&
+            FTy.getReturnType()->isIntegerTy(32));
   case LibFunc_setitimer:
     return (NumParams == 3 && FTy.getParamType(1)->isPointerTy() &&
             FTy.getParamType(2)->isPointerTy());

Added: llvm/trunk/test/Transforms/InstCombine/sprintf-void.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/sprintf-void.ll?rev=332106&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/sprintf-void.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/sprintf-void.ll Fri May 11 09:53:56 2018
@@ -0,0 +1,21 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+
+ at hello_world = constant [13 x i8] c"hello world\0A\00"
+
+declare void @sprintf(i8*, i8*, ...)
+
+; Check that a sprintf call, that would otherwise be optimized, but with
+; optimized out return type, doesn't crash the optimizer.
+
+define void @test_simplify1(i8* %dst) {
+; CHECK-LABEL: @test_simplify1(
+; CHECK-NEXT:    call void (i8*, i8*, ...) @sprintf(i8* [[DST:%.*]], i8* getelementptr inbounds ([13 x i8], [13 x i8]* @hello_world, i32 0, i32 0))
+; CHECK-NEXT:    ret void
+;
+  %fmt = getelementptr [13 x i8], [13 x i8]* @hello_world, i32 0, i32 0
+  call void (i8*, i8*, ...) @sprintf(i8* %dst, i8* %fmt)
+  ret void
+}