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[InstCombine] snprintf optimizations

Browse Source 
Reviewers: spatel, efriedma, majnemer, rja, bkramer

Reviewed By: rja, bkramer

Subscribers: mstorsjo, rja, llvm-commits

Differential Revision: https://reviews.llvm.org/D46285

llvm-svn: 332110
This commit is contained in:
David Bolvansky 2018-05-11 17:50:49 +00:00
parent de0ff1af6e
commit 1c3c8a0fe0
3 changed files with 230 additions and 0 deletions
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2
include/llvm/Transforms/Utils/SimplifyLibCalls.h
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@ -159,6 +159,7 @@ private:
int StreamArg = -1); int StreamArg = -1);
Value *optimizePrintF(CallInst *CI, IRBuilder<> &B); Value *optimizePrintF(CallInst *CI, IRBuilder<> &B);
Value *optimizeSPrintF(CallInst *CI, IRBuilder<> &B); Value *optimizeSPrintF(CallInst *CI, IRBuilder<> &B);
Value *optimizeSnPrintF(CallInst *CI, IRBuilder<> &B);
Value *optimizeFPrintF(CallInst *CI, IRBuilder<> &B); Value *optimizeFPrintF(CallInst *CI, IRBuilder<> &B);
Value *optimizeFWrite(CallInst *CI, IRBuilder<> &B); Value *optimizeFWrite(CallInst *CI, IRBuilder<> &B);
Value *optimizeFPuts(CallInst *CI, IRBuilder<> &B); Value *optimizeFPuts(CallInst *CI, IRBuilder<> &B);
@ -172,6 +173,7 @@ private:
SmallVectorImpl<CallInst *> &SinCosCalls); SmallVectorImpl<CallInst *> &SinCosCalls);
Value *optimizePrintFString(CallInst *CI, IRBuilder<> &B); Value *optimizePrintFString(CallInst *CI, IRBuilder<> &B);
Value *optimizeSPrintFString(CallInst *CI, IRBuilder<> &B); Value *optimizeSPrintFString(CallInst *CI, IRBuilder<> &B);
Value *optimizeSnPrintFString(CallInst *CI, IRBuilder<> &B);
Value *optimizeFPrintFString(CallInst *CI, IRBuilder<> &B); Value *optimizeFPrintFString(CallInst *CI, IRBuilder<> &B);
/// hasFloatVersion - Checks if there is a float version of the specified /// hasFloatVersion - Checks if there is a float version of the specified

90
lib/Transforms/Utils/SimplifyLibCalls.cpp
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@ -1912,6 +1912,94 @@ Value *LibCallSimplifier::optimizeSPrintF(CallInst *CI, IRBuilder<> &B) {
return nullptr; return nullptr;
} }
Value *LibCallSimplifier::optimizeSnPrintFString(CallInst *CI, IRBuilder<> &B) {
// Check for a fixed format string.
StringRef FormatStr;
if (!getConstantStringInfo(CI->getArgOperand(2), FormatStr))
return nullptr;
// Check for size
ConstantInt *Size = dyn_cast<ConstantInt>(CI->getArgOperand(1));
if (!Size)
return nullptr;
uint64_t N = Size->getZExtValue();
// If we just have a format string (nothing else crazy) transform it.
if (CI->getNumArgOperands() == 3) {
// Make sure there's no % in the constant array. We could try to handle
// %% -> % in the future if we cared.
for (unsigned i = 0, e = FormatStr.size(); i != e; ++i)
if (FormatStr[i] == '%')
return nullptr; // we found a format specifier, bail out.
if (N == 0)
return ConstantInt::get(CI->getType(), FormatStr.size());
else if (N < FormatStr.size() + 1)
return nullptr;
// sprintf(str, size, fmt) -> llvm.memcpy(align 1 str, align 1 fmt,
// strlen(fmt)+1)
B.CreateMemCpy(
CI->getArgOperand(0), 1, CI->getArgOperand(2), 1,
ConstantInt::get(DL.getIntPtrType(CI->getContext()),
FormatStr.size() + 1)); // Copy the null byte.
return ConstantInt::get(CI->getType(), FormatStr.size());
}
// The remaining optimizations require the format string to be "%s" or "%c"
// and have an extra operand.
if (FormatStr.size() == 2 && FormatStr[0] == '%' &&
CI->getNumArgOperands() == 4) {
// Decode the second character of the format string.
if (FormatStr[1] == 'c') {
if (N == 0)
return ConstantInt::get(CI->getType(), 1);
else if (N == 1)
return nullptr;
// snprintf(dst, size, "%c", chr) --> *(i8*)dst = chr; *((i8*)dst+1) = 0
if (!CI->getArgOperand(3)->getType()->isIntegerTy())
return nullptr;
Value *V = B.CreateTrunc(CI->getArgOperand(3), B.getInt8Ty(), "char");
Value *Ptr = castToCStr(CI->getArgOperand(0), B);
B.CreateStore(V, Ptr);
Ptr = B.CreateGEP(B.getInt8Ty(), Ptr, B.getInt32(1), "nul");
B.CreateStore(B.getInt8(0), Ptr);
return ConstantInt::get(CI->getType(), 1);
}
if (FormatStr[1] == 's') {
// snprintf(dest, size, "%s", str) to llvm.memcpy(dest, str, len+1, 1)
StringRef Str;
if (!getConstantStringInfo(CI->getArgOperand(3), Str))
return nullptr;
if (N == 0)
return ConstantInt::get(CI->getType(), Str.size());
else if (N < Str.size() + 1)
return nullptr;
B.CreateMemCpy(CI->getArgOperand(0), 1, CI->getArgOperand(3), 1,
ConstantInt::get(CI->getType(), Str.size() + 1));
// The snprintf result is the unincremented number of bytes in the string.
return ConstantInt::get(CI->getType(), Str.size());
}
}
return nullptr;
}
Value *LibCallSimplifier::optimizeSnPrintF(CallInst *CI, IRBuilder<> &B) {
if (Value *V = optimizeSnPrintFString(CI, B)) {
return V;
}
return nullptr;
}
Value *LibCallSimplifier::optimizeFPrintFString(CallInst *CI, IRBuilder<> &B) { Value *LibCallSimplifier::optimizeFPrintFString(CallInst *CI, IRBuilder<> &B) {
optimizeErrorReporting(CI, B, 0); optimizeErrorReporting(CI, B, 0);
@ -2318,6 +2406,8 @@ Value *LibCallSimplifier::optimizeCall(CallInst *CI) {
return optimizePrintF(CI, Builder); return optimizePrintF(CI, Builder);
case LibFunc_sprintf: case LibFunc_sprintf:
return optimizeSPrintF(CI, Builder); return optimizeSPrintF(CI, Builder);
case LibFunc_snprintf:
return optimizeSnPrintF(CI, Builder);
case LibFunc_fprintf: case LibFunc_fprintf:
return optimizeFPrintF(CI, Builder); return optimizeFPrintF(CI, Builder);
case LibFunc_fwrite: case LibFunc_fwrite:

138
test/Transforms/InstCombine/snprintf.ll Normal file
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@ -0,0 +1,138 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -instcombine -S | FileCheck %s
@.str = private unnamed_addr constant [4 x i8] c"str\00", align 1
@.str.1 = private unnamed_addr constant [3 x i8] c"%%\00", align 1
@.str.2 = private unnamed_addr constant [3 x i8] c"%c\00", align 1
@.str.3 = private unnamed_addr constant [3 x i8] c"%s\00", align 1
declare i32 @snprintf(i8*, i64, i8*, ...) #1
define void @test_not_const_fmt(i8* %buf, i8* %fmt) #0 {
; CHECK-LABEL: @test_not_const_fmt(
; CHECK-NEXT: [[CALL:%.*]] = call i32 (i8*, i64, i8*, ...) @snprintf(i8* [[BUF:%.*]], i64 32, i8* [[FMT:%.*]])
; CHECK-NEXT: ret void
;
%call = call i32 (i8*, i64, i8*, ...) @snprintf(i8* %buf, i64 32, i8* %fmt) #2
ret void
}
define void @test_not_const_fmt_zero_size_return_value(i8* %buf, i8* %fmt) #0 {
; CHECK-LABEL: @test_not_const_fmt_zero_size_return_value(
; CHECK-NEXT: [[CALL:%.*]] = call i32 (i8*, i64, i8*, ...) @snprintf(i8* [[BUF:%.*]], i64 0, i8* [[FMT:%.*]])
; CHECK-NEXT: ret void
;
%call = call i32 (i8*, i64, i8*, ...) @snprintf(i8* %buf, i64 0, i8* %fmt) #2
ret void
}
define void @test_not_const_size(i8* %buf, i64 %size) #0 {
; CHECK-LABEL: @test_not_const_size(
; CHECK-NEXT: [[CALL:%.*]] = call i32 (i8*, i64, i8*, ...) @snprintf(i8* [[BUF:%.*]], i64 [[SIZE:%.*]], i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0))
; CHECK-NEXT: ret void
;
%call = call i32 (i8*, i64, i8*, ...) @snprintf(i8* %buf, i64 %size, i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0)) #2
ret void
}
define i32 @test_return_value(i8* %buf) #0 {
; CHECK-LABEL: @test_return_value(
; CHECK-NEXT: ret i32 3
;
%call = call i32 (i8*, i64, i8*, ...) @snprintf(i8* %buf, i64 0, i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0)) #2
ret i32 %call
}
define void @test_percentage(i8* %buf) #0 {
; CHECK-LABEL: @test_percentage(
; CHECK-NEXT: [[CALL:%.*]] = call i32 (i8*, i64, i8*, ...) @snprintf(i8* [[BUF:%.*]], i64 32, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.1, i64 0, i64 0))
; CHECK-NEXT: ret void
;
%call = call i32 (i8*, i64, i8*, ...) @snprintf(i8* %buf, i64 32, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.1, i64 0, i64 0)) #2
ret void
}
define i32 @test_null_buf_return_value() #0 {
; CHECK-LABEL: @test_null_buf_return_value(
; CHECK-NEXT: ret i32 3
;
%call = call i32 (i8*, i64, i8*, ...) @snprintf(i8* null, i64 0, i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0)) #2
ret i32 %call
}
define i32 @test_percentage_return_value() #0 {
; CHECK-LABEL: @test_percentage_return_value(
; CHECK-NEXT: [[CALL:%.*]] = call i32 (i8*, i64, i8*, ...) @snprintf(i8* null, i64 0, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.1, i64 0, i64 0))
; CHECK-NEXT: ret i32 [[CALL]]
;
%call = call i32 (i8*, i64, i8*, ...) @snprintf(i8* null, i64 0, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.1, i64 0, i64 0)) #3
ret i32 %call
}
define void @test_correct_copy(i8* %buf) #0 {
; CHECK-LABEL: @test_correct_copy(
; CHECK-NEXT: [[TMP1:%.*]] = bitcast i8* [[BUF:%.*]] to i32*
; CHECK-NEXT: store i32 7500915, i32* [[TMP1]], align 1
; CHECK-NEXT: ret void
;
%call = call i32 (i8*, i64, i8*, ...) @snprintf(i8* %buf, i64 32, i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0)) #2
ret void
}
define i32 @test_char_zero_size(i8* %buf) #0 {
; CHECK-LABEL: @test_char_zero_size(
; CHECK-NEXT: ret i32 1
;
%call = call i32 (i8*, i64, i8*, ...) @snprintf(i8* %buf, i64 0, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.2, i64 0, i64 0), i32 65) #2
ret i32 %call
}
define i32 @test_char_wrong_size(i8* %buf) #0 {
; CHECK-LABEL: @test_char_wrong_size(
; CHECK-NEXT: [[CALL:%.*]] = call i32 (i8*, i64, i8*, ...) @snprintf(i8* [[BUF:%.*]], i64 1, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.2, i64 0, i64 0), i32 65)
; CHECK-NEXT: ret i32 [[CALL]]
;
%call = call i32 (i8*, i64, i8*, ...) @snprintf(i8* %buf, i64 1, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.2, i64 0, i64 0), i32 65) #2
ret i32 %call
}
define i32 @test_char_ok_size(i8* %buf) #0 {
; CHECK-LABEL: @test_char_ok_size(
; CHECK-NEXT: store i8 65, i8* [[BUF:%.*]], align 1
; CHECK-NEXT: [[NUL:%.*]] = getelementptr i8, i8* [[BUF]], i64 1
; CHECK-NEXT: store i8 0, i8* [[NUL]], align 1
; CHECK-NEXT: ret i32 1
;
%call = call i32 (i8*, i64, i8*, ...) @snprintf(i8* %buf, i64 32, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.2, i64 0, i64 0), i32 65) #2
ret i32 %call
}
define i32 @test_str_zero_size(i8* %buf) #0 {
; CHECK-LABEL: @test_str_zero_size(
; CHECK-NEXT: ret i32 3
;
%call = call i32 (i8*, i64, i8*, ...) @snprintf(i8* %buf, i64 0, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.3, i64 0, i64 0), i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0)) #2
ret i32 %call
}
define i32 @test_str_wrong_size(i8* %buf) #0 {
; CHECK-LABEL: @test_str_wrong_size(
; CHECK-NEXT: [[CALL:%.*]] = call i32 (i8*, i64, i8*, ...) @snprintf(i8* [[BUF:%.*]], i64 1, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.3, i64 0, i64 0), i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0))
; CHECK-NEXT: ret i32 [[CALL]]
;
%call = call i32 (i8*, i64, i8*, ...) @snprintf(i8* %buf, i64 1, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.3, i64 0, i64 0), i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0)) #2
ret i32 %call
}
define i32 @test_str_ok_size(i8* %buf) #0 {
; CHECK-LABEL: @test_str_ok_size(
; CHECK-NEXT: [[TMP1:%.*]] = bitcast i8* [[BUF:%.*]] to i32*
; CHECK-NEXT: store i32 7500915, i32* [[TMP1]], align 1
; CHECK-NEXT: ret i32 3
;
%call = call i32 (i8*, i64, i8*, ...) @snprintf(i8* %buf, i64 32, i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.3, i64 0, i64 0), i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0)) #2
ret i32 %call
}