[SLPVectorizer] Check that lowered type is floating point before calling isFabsFree

sbc100 · sbc100 · commit 81abca32fba4 · 2018-10-09T18:41:17.000Z
In the case of soft-fp (e.g. fp128 under wasm) the result of getTypeLegalizationCost() can be an integer type even if the input is floating point (See LegalizeTypeAction::TypeSoftenFloat). Before calling isFabsFree() (which asserts if given a non-fp type) we need to check that that result is fp. This is safe since in fabs is certainly not free in the soft-fp case. Fixes PR39168 Differential Revision: https://reviews.llvm.org/D52899 llvm-svn: 344069
diff --git a/llvm/include/llvm/CodeGen/BasicTTIImpl.h b/llvm/include/llvm/CodeGen/BasicTTIImpl.h
@@ -1139,7 +1139,8 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
     SmallVector<unsigned, 2> CustomCost;
     for (unsigned ISD : ISDs) {
       if (TLI->isOperationLegalOrPromote(ISD, LT.second)) {
-        if (IID == Intrinsic::fabs && TLI->isFAbsFree(LT.second)) {
+        if (IID == Intrinsic::fabs && LT.second.isFloatingPoint() &&
+            TLI->isFAbsFree(LT.second)) {
           return 0;
         }
 
diff --git a/llvm/test/Transforms/SLPVectorizer/X86/fabs-cost-softfp.ll b/llvm/test/Transforms/SLPVectorizer/X86/fabs-cost-softfp.ll
@@ -0,0 +1,29 @@
+; Regression test from https://bugs.llvm.org/show_bug.cgi?id=39168
+; Based on code from `compiler-rt/lib/builtins/multc3.c`
+; On plaforms where fp128 lowers to an interger type (soft-fp) we
+; shouldn't be calling isFAbsFree() on the legalized type.
+
+; RUN: opt -slp-vectorizer -slp-threshold=-10 -S %s | FileCheck %s
+; CHECK: call <2 x fp128> @llvm.fabs.v2f128(<2 x fp128
+
+target triple = "i686-unknown-linux-gnu"
+
+define void @vectorize_fp128(fp128 %c, fp128 %d) #0 {
+entry:
+  %0 = tail call fp128 @llvm.fabs.f128(fp128 %c)
+  %cmpinf10 = fcmp oeq fp128 %0, 0xL00000000000000007FFF000000000000
+  %1 = tail call fp128 @llvm.fabs.f128(fp128 %d)
+  %cmpinf12 = fcmp oeq fp128 %1, 0xL00000000000000007FFF000000000000
+  %or.cond39 = or i1 %cmpinf10, %cmpinf12
+  br i1 %or.cond39, label %if.then13, label %if.end24
+
+if.then13:                                        ; preds = %entry
+  unreachable
+
+if.end24:                                         ; preds = %entry
+  ret void
+}
+
+declare fp128 @llvm.fabs.f128(fp128)
+
+attributes #0 = { "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" }

Original file line number	Diff line number	Diff line change
`@@ -1139,7 +1139,8 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {`
`1139`	`1139`	`SmallVector<unsigned, 2> CustomCost;`
`1140`	`1140`	`for (unsigned ISD : ISDs) {`
`1141`	`1141`	`if (TLI->isOperationLegalOrPromote(ISD, LT.second)) {`
`1142`		`- if (IID == Intrinsic::fabs && TLI->isFAbsFree(LT.second)) {`
	`1142`	`+ if (IID == Intrinsic::fabs && LT.second.isFloatingPoint() &&`
	`1143`	`+ TLI->isFAbsFree(LT.second)) {`
`1143`	`1144`	`return 0;`
`1144`	`1145`	`}`
`1145`	`1146`