diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp --- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp @@ -2377,14 +2377,22 @@ if (FormatStr.size() == 1 || FormatStr == "%%") return emitPutChar(B.getInt32(FormatStr[0]), B, TLI); - // printf("%s", "a") --> putchar('a') + // Try to emit putchar or puts. if (FormatStr == "%s" && CI->getNumArgOperands() > 1) { - StringRef ChrStr; - if (!getConstantStringInfo(CI->getOperand(1), ChrStr)) + StringRef OperandStr; + if (!getConstantStringInfo(CI->getOperand(1), OperandStr) || + OperandStr.empty()) return nullptr; - if (ChrStr.size() != 1) - return nullptr; - return emitPutChar(B.getInt32(ChrStr[0]), B, TLI); + // printf("%s", "a") --> putchar('a') + if (OperandStr.size() == 1) + return emitPutChar(B.getInt32(OperandStr[0]), B, TLI); + // printf("%s", str"\n") --> puts(str) + else if (OperandStr.back() == '\n') { + OperandStr = OperandStr.drop_back(); + Value *GV = B.CreateGlobalString(OperandStr, "str"); + return emitPutS(GV, B, TLI); + } + return nullptr; } // printf("foo\n") --> puts("foo") diff --git a/llvm/test/Transforms/InstCombine/printf-2.ll b/llvm/test/Transforms/InstCombine/printf-2.ll --- a/llvm/test/Transforms/InstCombine/printf-2.ll +++ b/llvm/test/Transforms/InstCombine/printf-2.ll @@ -56,3 +56,14 @@ call void (i8*, ...) @printf(i8* %fmt, i8* %str) ret void } + +define void @test_simplify8() { +; CHECK-LABEL: @test_simplify8( +; CHECK-NEXT: [[PUTS:%.*]] = call i32 @puts(i8* nonnull dereferenceable(1) getelementptr inbounds ([12 x i8], [12 x i8]* @str.1, i32 0, i32 0)) +; CHECK-NEXT: ret void +; + %fmt = getelementptr [3 x i8], [3 x i8]* @format_str, i32 0, i32 0 + %str = getelementptr [13 x i8], [13 x i8]* @hello_world, i32 0, i32 0 + call void (i8*, ...) @printf(i8* %fmt, i8* %str) + ret void +}