[LibCallSimplifier] use instruction-level fast-math-flags to transform sqrt calls

This is a continuation of adding FMF to call instructions:
http://reviews.llvm.org/rL255555

The intent of the patch is to preserve the current behavior of the transform except
that we use the sqrt instruction's 'fast' attribute as a trigger rather than the
function-level attribute.

But this raises a bug noted by the new FIXME comment.

In order to do this transform:
sqrt((x * x) * y) ---> fabs(x) * sqrt(y)

...we need all of the sqrt, the first fmul, and the second fmul to be 'fast'.
If any of those ops is strict, we should bail out.

Differential Revision: http://reviews.llvm.org/D15937

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@257400 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Utils/SimplifyLibCalls.cpp b/lib/Transforms/Utils/SimplifyLibCalls.cpp
index edf0db467aec0d3647751a2491e6288c711011c2..cf87ac1cf28bfead14b80bd1656c5bc7c47366b9 100644 (file)
--- a/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -1397,7 +1397,8 @@ Value *LibCallSimplifier::optimizeSqrt(CallInst *CI, IRBuilder<> &B) {
   if (TLI->has(LibFunc::sqrtf) && (Callee->getName() == "sqrt" ||
                                    Callee->getIntrinsicID() == Intrinsic::sqrt))
     Ret = optimizeUnaryDoubleFP(CI, B, true);
-  if (!canUseUnsafeFPMath(CI->getParent()->getParent()))
+
+  if (!CI->hasUnsafeAlgebra())
     return Ret;
 
   Instruction *I = dyn_cast<Instruction>(CI->getArgOperand(0));
@@ -1406,7 +1407,7 @@ Value *LibCallSimplifier::optimizeSqrt(CallInst *CI, IRBuilder<> &B) {
 
   // We're looking for a repeated factor in a multiplication tree,
   // so we can do this fold: sqrt(x * x) -> fabs(x);
-  // or this fold: sqrt(x * x * y) -> fabs(x) * sqrt(y).
+  // or this fold: sqrt((x * x) * y) -> fabs(x) * sqrt(y).
   Value *Op0 = I->getOperand(0);
   Value *Op1 = I->getOperand(1);
   Value *RepeatOp = nullptr;
@@ -1421,6 +1422,7 @@ Value *LibCallSimplifier::optimizeSqrt(CallInst *CI, IRBuilder<> &B) {
     // variations of this pattern because instcombine's visitFMUL and/or the
     // reassociation pass should give us this form.
     Value *OtherMul0, *OtherMul1;
+    // FIXME: This multiply must be unsafe to allow this transform.
     if (match(Op0, m_FMul(m_Value(OtherMul0), m_Value(OtherMul1)))) {
       // Pattern: sqrt((x * y) * z)
       if (OtherMul0 == OtherMul1) {
@@ -1435,8 +1437,6 @@ Value *LibCallSimplifier::optimizeSqrt(CallInst *CI, IRBuilder<> &B) {
 
   // Fast math flags for any created instructions should match the sqrt
   // and multiply.
-  // FIXME: We're not checking the sqrt because it doesn't have
-  // fast-math-flags (see earlier comment).
   IRBuilder<>::FastMathFlagGuard Guard(B);
   B.SetFastMathFlags(I->getFastMathFlags());
   // If we found a repeated factor, hoist it out of the square root and

diff --git a/test/Transforms/InstCombine/fast-math.ll b/test/Transforms/InstCombine/fast-math.ll
index 5bdf48b85ce78307a5c21b9790805b942e8243d3..b24ce278ca89f2a13b3fc6f88812256783203805 100644 (file)
--- a/test/Transforms/InstCombine/fast-math.ll
+++ b/test/Transforms/InstCombine/fast-math.ll
@@ -555,18 +555,12 @@ define float @fact_div6(float %x) {
 
 ; A squared factor fed into a square root intrinsic should be hoisted out
 ; as a fabs() value.
-; We have to rely on a function-level attribute to enable this optimization
-; because intrinsics don't currently have access to IR-level fast-math
-; flags. If that changes, we can relax the requirement on all of these
-; tests to just specify 'fast' on the sqrt.
-
-attributes #0 = { "unsafe-fp-math" = "true" }
 
 declare double @llvm.sqrt.f64(double)
 
-define double @sqrt_intrinsic_arg_squared(double %x) #0 {
+define double @sqrt_intrinsic_arg_squared(double %x) {
   %mul = fmul fast double %x, %x
-  %sqrt = call double @llvm.sqrt.f64(double %mul)
+  %sqrt = call fast double @llvm.sqrt.f64(double %mul)
   ret double %sqrt
 
 ; CHECK-LABEL: sqrt_intrinsic_arg_squared(
@@ -577,10 +571,10 @@ define double @sqrt_intrinsic_arg_squared(double %x) #0 {
 ; Check all 6 combinations of a 3-way multiplication tree where
 ; one factor is repeated.
 
-define double @sqrt_intrinsic_three_args1(double %x, double %y) #0 {
+define double @sqrt_intrinsic_three_args1(double %x, double %y) {
   %mul = fmul fast double %y, %x
   %mul2 = fmul fast double %mul, %x
-  %sqrt = call double @llvm.sqrt.f64(double %mul2)
+  %sqrt = call fast double @llvm.sqrt.f64(double %mul2)
   ret double %sqrt
 
 ; CHECK-LABEL: sqrt_intrinsic_three_args1(
@@ -590,10 +584,10 @@ define double @sqrt_intrinsic_three_args1(double %x, double %y) #0 {
 ; CHECK-NEXT: ret double %1
 }
 
-define double @sqrt_intrinsic_three_args2(double %x, double %y) #0 {
+define double @sqrt_intrinsic_three_args2(double %x, double %y) {
   %mul = fmul fast double %x, %y
   %mul2 = fmul fast double %mul, %x
-  %sqrt = call double @llvm.sqrt.f64(double %mul2)
+  %sqrt = call fast double @llvm.sqrt.f64(double %mul2)
   ret double %sqrt
 
 ; CHECK-LABEL: sqrt_intrinsic_three_args2(
@@ -603,10 +597,10 @@ define double @sqrt_intrinsic_three_args2(double %x, double %y) #0 {
 ; CHECK-NEXT: ret double %1
 }
 
-define double @sqrt_intrinsic_three_args3(double %x, double %y) #0 {
+define double @sqrt_intrinsic_three_args3(double %x, double %y) {
   %mul = fmul fast double %x, %x
   %mul2 = fmul fast double %mul, %y
-  %sqrt = call double @llvm.sqrt.f64(double %mul2)
+  %sqrt = call fast double @llvm.sqrt.f64(double %mul2)
   ret double %sqrt
 
 ; CHECK-LABEL: sqrt_intrinsic_three_args3(
@@ -616,10 +610,10 @@ define double @sqrt_intrinsic_three_args3(double %x, double %y) #0 {
 ; CHECK-NEXT: ret double %1
 }
 
-define double @sqrt_intrinsic_three_args4(double %x, double %y) #0 {
+define double @sqrt_intrinsic_three_args4(double %x, double %y) {
   %mul = fmul fast double %y, %x
   %mul2 = fmul fast double %x, %mul
-  %sqrt = call double @llvm.sqrt.f64(double %mul2)
+  %sqrt = call fast double @llvm.sqrt.f64(double %mul2)
   ret double %sqrt
 
 ; CHECK-LABEL: sqrt_intrinsic_three_args4(
@@ -629,10 +623,10 @@ define double @sqrt_intrinsic_three_args4(double %x, double %y) #0 {
 ; CHECK-NEXT: ret double %1
 }
 
-define double @sqrt_intrinsic_three_args5(double %x, double %y) #0 {
+define double @sqrt_intrinsic_three_args5(double %x, double %y) {
   %mul = fmul fast double %x, %y
   %mul2 = fmul fast double %x, %mul
-  %sqrt = call double @llvm.sqrt.f64(double %mul2)
+  %sqrt = call fast double @llvm.sqrt.f64(double %mul2)
   ret double %sqrt
 
 ; CHECK-LABEL: sqrt_intrinsic_three_args5(
@@ -642,10 +636,10 @@ define double @sqrt_intrinsic_three_args5(double %x, double %y) #0 {
 ; CHECK-NEXT: ret double %1
 }
 
-define double @sqrt_intrinsic_three_args6(double %x, double %y) #0 {
+define double @sqrt_intrinsic_three_args6(double %x, double %y) {
   %mul = fmul fast double %x, %x
   %mul2 = fmul fast double %y, %mul
-  %sqrt = call double @llvm.sqrt.f64(double %mul2)
+  %sqrt = call fast double @llvm.sqrt.f64(double %mul2)
   ret double %sqrt
 
 ; CHECK-LABEL: sqrt_intrinsic_three_args6(
@@ -655,10 +649,10 @@ define double @sqrt_intrinsic_three_args6(double %x, double %y) #0 {
 ; CHECK-NEXT: ret double %1
 }
 
-define double @sqrt_intrinsic_arg_4th(double %x) #0 {
+define double @sqrt_intrinsic_arg_4th(double %x) {
   %mul = fmul fast double %x, %x
   %mul2 = fmul fast double %mul, %mul
-  %sqrt = call double @llvm.sqrt.f64(double %mul2)
+  %sqrt = call fast double @llvm.sqrt.f64(double %mul2)
   ret double %sqrt
 
 ; CHECK-LABEL: sqrt_intrinsic_arg_4th(
@@ -666,11 +660,11 @@ define double @sqrt_intrinsic_arg_4th(double %x) #0 {
 ; CHECK-NEXT: ret double %mul
 }
 
-define double @sqrt_intrinsic_arg_5th(double %x) #0 {
+define double @sqrt_intrinsic_arg_5th(double %x) {
   %mul = fmul fast double %x, %x
   %mul2 = fmul fast double %mul, %x
   %mul3 = fmul fast double %mul2, %mul
-  %sqrt = call double @llvm.sqrt.f64(double %mul3)
+  %sqrt = call fast double @llvm.sqrt.f64(double %mul3)
   ret double %sqrt
 
 ; CHECK-LABEL: sqrt_intrinsic_arg_5th(
@@ -686,9 +680,9 @@ declare float @sqrtf(float)
 declare double @sqrt(double)
 declare fp128 @sqrtl(fp128)
 
-define float @sqrt_call_squared_f32(float %x) #0 {
+define float @sqrt_call_squared_f32(float %x) {
   %mul = fmul fast float %x, %x
-  %sqrt = call float @sqrtf(float %mul)
+  %sqrt = call fast float @sqrtf(float %mul)
   ret float %sqrt
 
 ; CHECK-LABEL: sqrt_call_squared_f32(
@@ -696,9 +690,9 @@ define float @sqrt_call_squared_f32(float %x) #0 {
 ; CHECK-NEXT: ret float %fabs
 }
 
-define double @sqrt_call_squared_f64(double %x) #0 {
+define double @sqrt_call_squared_f64(double %x) {
   %mul = fmul fast double %x, %x
-  %sqrt = call double @sqrt(double %mul)
+  %sqrt = call fast double @sqrt(double %mul)
   ret double %sqrt
 
 ; CHECK-LABEL: sqrt_call_squared_f64(
@@ -706,9 +700,9 @@ define double @sqrt_call_squared_f64(double %x) #0 {
 ; CHECK-NEXT: ret double %fabs
 }
 
-define fp128 @sqrt_call_squared_f128(fp128 %x) #0 {
+define fp128 @sqrt_call_squared_f128(fp128 %x) {
   %mul = fmul fast fp128 %x, %x
-  %sqrt = call fp128 @sqrtl(fp128 %mul)
+  %sqrt = call fast fp128 @sqrtl(fp128 %mul)
   ret fp128 %sqrt
 
 ; CHECK-LABEL: sqrt_call_squared_f128(

diff --git a/test/Transforms/InstCombine/inline-intrinsic-assert.ll b/test/Transforms/InstCombine/inline-intrinsic-assert.ll
index c6446d43cffd816b7aee66122f593e07ab945b66..8eecb3fd40aa0189e14da9e53e3261d0085f25b1 100644 (file)
--- a/test/Transforms/InstCombine/inline-intrinsic-assert.ll
+++ b/test/Transforms/InstCombine/inline-intrinsic-assert.ll
@@ -4,7 +4,7 @@
 ; The inliner should not add an edge to an intrinsic and
 ; then assert that it did not add an edge to an intrinsic!
 
-define float @foo(float %f1) #0 {
+define float @foo(float %f1) {
   %call = call float @bar(float %f1)
   ret float %call
 
@@ -13,18 +13,16 @@ define float @foo(float %f1) #0 {
 ; CHECK-NEXT: ret float
 }
 
-define float @bar(float %f1) #0 {
+define float @bar(float %f1) {
   %call = call float @sqr(float %f1)
-  %call1 = call float @sqrtf(float %call) #0
+  %call1 = call fast float @sqrtf(float %call)
   ret float %call1
 }
 
-define float @sqr(float %f) #0 {
+define float @sqr(float %f) {
   %mul = fmul fast float %f, %f
   ret float %mul
 }
 
-declare float @sqrtf(float) #0
-
-attributes #0 = { "unsafe-fp-math"="true" }
+declare float @sqrtf(float)
 

diff --git a/test/Transforms/InstCombine/no_cgscc_assert.ll b/test/Transforms/InstCombine/no_cgscc_assert.ll
index 3df04d2c8902f33d6bd239c3e121c6b744e78df2..677066fa2ab0708b68dd42631ab333279885464e 100644 (file)
--- a/test/Transforms/InstCombine/no_cgscc_assert.ll
+++ b/test/Transforms/InstCombine/no_cgscc_assert.ll
@@ -6,7 +6,7 @@
 
 define float @bar(float %f) #0 {
   %mul = fmul fast float %f, %f
-  %call1 = call float @sqrtf(float %mul) #0
+  %call1 = call fast float @sqrtf(float %mul)
   ret float %call1
 
 ; CHECK-LABEL: @bar(
@@ -14,6 +14,5 @@ define float @bar(float %f) #0 {
 ; CHECK-NEXT: ret float
 }
 
-declare float @sqrtf(float) #0
+declare float @sqrtf(float)
 
-attributes #0 = { readnone "unsafe-fp-math"="true" }