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https://github.com/RPCS3/llvm-mirror.git
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b86cbf7581
This commit introduces a set of experimental intrinsics intended to prevent optimizations that make assumptions about the rounding mode and floating point exception behavior. These intrinsics will later be extended to specify flush-to-zero behavior. More work is also required to model instruction dependencies in machine code and to generate these instructions from clang (when required by pragmas and/or command line options that are not currently supported). Differential Revision: https://reviews.llvm.org/D27028 llvm-svn: 293226
103 lines
3.9 KiB
LLVM
103 lines
3.9 KiB
LLVM
; RUN: opt -O3 -S < %s | FileCheck %s
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; Test to verify that constants aren't folded when the rounding mode is unknown.
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; CHECK-LABEL: @f1
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; CHECK: call double @llvm.experimental.constrained.fdiv.f64
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define double @f1() {
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entry:
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%div = call double @llvm.experimental.constrained.fdiv.f64(
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double 1.000000e+00,
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double 1.000000e+01,
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metadata !"round.dynamic",
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metadata !"fpexcept.strict")
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ret double %div
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}
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; Verify that 'a - 0' isn't simplified to 'a' when the rounding mode is unknown.
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;
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; double f2(double a) {
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; // Because the result of '0 - 0' is negative zero if rounding mode is
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; // downward, this shouldn't be simplified.
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; return a - 0.0;
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; }
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;
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; CHECK-LABEL: @f2
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; CHECK: call double @llvm.experimental.constrained.fsub.f64
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define double @f2(double %a) {
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entry:
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%div = call double @llvm.experimental.constrained.fsub.f64(
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double %a, double 0.000000e+00,
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metadata !"round.dynamic",
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metadata !"fpexcept.strict")
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ret double %div
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}
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; Verify that '-((-a)*b)' isn't simplified to 'a*b' when the rounding mode is
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; unknown.
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;
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; double f3(double a, double b) {
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; // Because the intermediate value involved in this calculation may require
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; // rounding, this shouldn't be simplified.
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; return -((-a)*b);
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; }
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;
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; CHECK-LABEL: @f3
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; CHECK: call double @llvm.experimental.constrained.fsub.f64
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; CHECK: call double @llvm.experimental.constrained.fmul.f64
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; CHECK: call double @llvm.experimental.constrained.fsub.f64
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define double @f3(double %a, double %b) {
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entry:
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%sub = call double @llvm.experimental.constrained.fsub.f64(
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double -0.000000e+00, double %a,
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metadata !"round.dynamic",
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metadata !"fpexcept.strict")
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%mul = call double @llvm.experimental.constrained.fmul.f64(
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double %sub, double %b,
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metadata !"round.dynamic",
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metadata !"fpexcept.strict")
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%ret = call double @llvm.experimental.constrained.fsub.f64(
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double -0.000000e+00,
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double %mul,
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metadata !"round.dynamic",
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metadata !"fpexcept.strict")
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ret double %ret
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}
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; Verify that FP operations are not performed speculatively when FP exceptions
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; are not being ignored.
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;
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; double f4(int n, double a) {
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; // Because a + 1 may overflow, this should not be simplified.
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; if (n > 0)
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; return a + 1.0;
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; return a;
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; }
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;
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;
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; CHECK-LABEL: @f4
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; CHECK-NOT: select
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; CHECK: br i1 %cmp
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define double @f4(i32 %n, double %a) {
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entry:
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%cmp = icmp sgt i32 %n, 0
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br i1 %cmp, label %if.then, label %if.end
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if.then:
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%add = call double @llvm.experimental.constrained.fadd.f64(
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double 1.000000e+00, double %a,
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metadata !"round.dynamic",
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metadata !"fpexcept.strict")
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br label %if.end
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if.end:
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%a.0 = phi double [%add, %if.then], [ %a, %entry ]
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ret double %a.0
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}
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@llvm.fp.env = thread_local global i8 zeroinitializer, section "llvm.metadata"
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declare double @llvm.experimental.constrained.fdiv.f64(double, double, metadata, metadata)
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declare double @llvm.experimental.constrained.fmul.f64(double, double, metadata, metadata)
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declare double @llvm.experimental.constrained.fadd.f64(double, double, metadata, metadata)
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declare double @llvm.experimental.constrained.fsub.f64(double, double, metadata, metadata)
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