don't hoist FP additions into unconditional adds + selects. This
could theoretically introduce a trap, but is also a performance issue.
This speeds up ptrdist/ks by 8%.
llvm-svn: 45533
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index b838f94..f19adbd 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -372,6 +372,8 @@
case Instruction::AShr:
case Instruction::ICmp:
case Instruction::FCmp:
+ if (I->getOperand(0)->getType()->isFPOrFPVector())
+ return false; // FP arithmetic might trap.
break; // These are all cheap and non-trapping instructions.
}
diff --git a/llvm/test/Transforms/SimplifyCFG/2008-01-02-hoist-fp-add.ll b/llvm/test/Transforms/SimplifyCFG/2008-01-02-hoist-fp-add.ll
new file mode 100644
index 0000000..43ff690
--- /dev/null
+++ b/llvm/test/Transforms/SimplifyCFG/2008-01-02-hoist-fp-add.ll
@@ -0,0 +1,26 @@
+; The phi should not be eliminated in this case, because the fp op could trap.
+; RUN: llvm-as < %s | opt -simplifycfg | llvm-dis | grep {= phi double}
+
+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"
+target triple = "i686-apple-darwin8"
+@G = weak global double 0.000000e+00, align 8 ; <double*> [#uses=2]
+
+define void @test(i32 %X, i32 %Y, double %Z) {
+entry:
+ %"alloca point" = bitcast i32 0 to i32 ; <i32> [#uses=0]
+ %tmp = load double* @G, align 8 ; <double> [#uses=2]
+ %tmp3 = icmp eq i32 %X, %Y ; <i1> [#uses=1]
+ %tmp34 = zext i1 %tmp3 to i8 ; <i8> [#uses=1]
+ %toBool = icmp ne i8 %tmp34, 0 ; <i1> [#uses=1]
+ br i1 %toBool, label %cond_true, label %cond_next
+
+cond_true: ; preds = %entry
+ %tmp7 = add double %tmp, %Z ; <double> [#uses=1]
+ br label %cond_next
+
+cond_next: ; preds = %cond_true, %entry
+ %F.0 = phi double [ %tmp, %entry ], [ %tmp7, %cond_true ] ; <double> [#uses=1]
+ store double %F.0, double* @G, align 8
+ ret void
+}
+