Conditionally eliminate library calls where the result value is not used

Summary:
This pass shrink-wraps a condition to some library calls where the call
result is not used. For example:
   sqrt(val);
 is transformed to
   if (val < 0)
     sqrt(val);
Even if the result of library call is not being used, the compiler cannot
safely delete the call because the function can set errno on error
conditions.
Note in many functions, the error condition solely depends on the incoming
parameter. In this optimization, we can generate the condition can lead to
the errno to shrink-wrap the call. Since the chances of hitting the error
condition is low, the runtime call is effectively eliminated.

These partially dead calls are usually results of C++ abstraction penalty
exposed by inlining. This optimization hits 108 times in 19 C/C++ programs
in SPEC2006.

Reviewers: hfinkel, mehdi_amini, davidxl

Subscribers: modocache, mgorny, mehdi_amini, xur, llvm-commits, beanz

Differential Revision: https://reviews.llvm.org/D24414

llvm-svn: 284542

1 files changed, 192 insertions, 0 deletions

diff --git a/llvm/test/Transforms/Util/libcalls-shrinkwrap-long-double.ll b/llvm/test/Transforms/Util/libcalls-shrinkwrap-long-double.ll
new file mode 100644
index 00000000000..54a31e5173f
--- /dev/null
+++ b/llvm/test/Transforms/Util/libcalls-shrinkwrap-long-double.ll
@@ -0,0 +1,192 @@
+; RUN: opt < %s -libcalls-shrinkwrap -S | FileCheck %s
+; New PM
+; RUN: opt < %s -passes=libcalls-shrinkwrap -S | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @test_range_error(x86_fp80 %value) {
+entry:
+  %call_0 = call x86_fp80 @coshl(x86_fp80 %value)
+; CHECK: [[COND1:%[0-9]+]] = fcmp olt x86_fp80 %value, 0xKC00CB174000000000000
+; CHECK: [[COND2:%[0-9]+]] = fcmp ogt x86_fp80 %value, 0xK400CB174000000000000
+; CHECK: [[COND:%[0-9]+]] = or i1 [[COND2]], [[COND1]]
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT:[0-9]+]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_0 = call x86_fp80 @coshl(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  %call_1 = call x86_fp80 @expl(x86_fp80 %value)
+; CHECK: [[COND1:%[0-9]+]] = fcmp olt x86_fp80 %value, 0xKC00CB21C000000000000
+; CHECK: [[COND2:%[0-9]+]] = fcmp ogt x86_fp80 %value, 0xK400CB170000000000000
+; CHECK: [[COND:%[0-9]+]] = or i1 [[COND2]], [[COND1]]
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_1 = call x86_fp80 @expl(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  %call_3 = call x86_fp80 @exp2l(x86_fp80 %value)
+; CHECK: [[COND1:%[0-9]+]] = fcmp olt x86_fp80 %value, 0xKC00D807A000000000000
+; CHECK: [[COND2:%[0-9]+]] = fcmp ogt x86_fp80 %value, 0xK400CB1DC000000000000
+; CHECK: [[COND:%[0-9]+]] = or i1 [[COND2]], [[COND1]]
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_3 = call x86_fp80 @exp2l(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  %call_4 = call x86_fp80 @sinhl(x86_fp80 %value)
+; CHECK: [[COND1:%[0-9]+]] = fcmp olt x86_fp80 %value, 0xKC00CB174000000000000
+; CHECK: [[COND2:%[0-9]+]] = fcmp ogt x86_fp80 %value, 0xK400CB174000000000000
+; CHECK: [[COND:%[0-9]+]] = or i1 [[COND2]], [[COND1]]
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_4 = call x86_fp80 @sinhl(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  %call_5 = call x86_fp80 @expm1l(x86_fp80 %value)
+; CHECK: [[COND:%[0-9]+]] = fcmp ogt x86_fp80 %value, 0xK400CB170000000000000
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_5 = call x86_fp80 @expm1l(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  ret void
+}
+
+declare x86_fp80 @coshl(x86_fp80)
+declare x86_fp80 @expl(x86_fp80)
+declare x86_fp80 @exp10l(x86_fp80)
+declare x86_fp80 @exp2l(x86_fp80)
+declare x86_fp80 @sinhl(x86_fp80)
+declare x86_fp80 @expm1l(x86_fp80)
+
+define void @test_domain_error(x86_fp80 %value) {
+entry:
+  %call_00 = call x86_fp80 @acosl(x86_fp80 %value)
+; CHECK: [[COND1:%[0-9]+]] = fcmp ogt x86_fp80 %value, 0xK3FFF8000000000000000
+; CHECK: [[COND2:%[0-9]+]] = fcmp olt x86_fp80 %value, 0xKBFFF8000000000000000
+; CHECK: [[COND:%[0-9]+]] = or i1 [[COND2]], [[COND1]]
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_00 = call x86_fp80 @acosl(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  %call_01 = call x86_fp80 @asinl(x86_fp80 %value)
+; CHECK: [[COND1:%[0-9]+]] = fcmp ogt x86_fp80 %value, 0xK3FFF8000000000000000
+; CHECK: [[COND2:%[0-9]+]] = fcmp olt x86_fp80 %value, 0xKBFFF8000000000000000
+; CHECK: [[COND:%[0-9]+]] = or i1 [[COND2]], [[COND1]]
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_01 = call x86_fp80 @asinl(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  %call_02 = call x86_fp80 @cosl(x86_fp80 %value)
+; CHECK: [[COND1:%[0-9]+]] = fcmp oeq x86_fp80 %value, 0xKFFFF8000000000000000
+; CHECK: [[COND2:%[0-9]+]] = fcmp oeq x86_fp80 %value, 0xK7FFF8000000000000000
+; CHECK: [[COND:%[0-9]+]] = or i1 [[COND2]], [[COND1]]
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_02 = call x86_fp80 @cosl(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  %call_03 = call x86_fp80 @sinl(x86_fp80 %value)
+; CHECK: [[COND1:%[0-9]+]] = fcmp oeq x86_fp80 %value, 0xKFFFF8000000000000000
+; CHECK: [[COND2:%[0-9]+]] = fcmp oeq x86_fp80 %value, 0xK7FFF8000000000000000
+; CHECK: [[COND:%[0-9]+]] = or i1 [[COND2]], [[COND1]]
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_03 = call x86_fp80 @sinl(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  %call_04 = call x86_fp80 @acoshl(x86_fp80 %value)
+; CHECK: [[COND:%[0-9]+]] = fcmp olt x86_fp80 %value, 0xK3FFF8000000000000000
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_04 = call x86_fp80 @acoshl(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  %call_05 = call x86_fp80 @sqrtl(x86_fp80 %value)
+; CHECK: [[COND:%[0-9]+]] = fcmp olt x86_fp80 %value, 0xK00000000000000000000
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_05 = call x86_fp80 @sqrtl(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  %call_06 = call x86_fp80 @atanhl(x86_fp80 %value)
+; CHECK: [[COND1:%[0-9]+]] = fcmp oge x86_fp80 %value, 0xK3FFF8000000000000000
+; CHECK: [[COND2:%[0-9]+]] = fcmp ole x86_fp80 %value, 0xKBFFF8000000000000000
+; CHECK: [[COND:%[0-9]+]] = or i1 [[COND2]], [[COND1]]
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_06 = call x86_fp80 @atanhl(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  %call_07 = call x86_fp80 @logl(x86_fp80 %value)
+; CHECK: [[COND:%[0-9]+]] = fcmp ole x86_fp80 %value, 0xK00000000000000000000
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_07 = call x86_fp80 @logl(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  %call_08 = call x86_fp80 @log10l(x86_fp80 %value)
+; CHECK: [[COND:%[0-9]+]] = fcmp ole x86_fp80 %value, 0xK00000000000000000000
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_08 = call x86_fp80 @log10l(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  %call_09 = call x86_fp80 @log2l(x86_fp80 %value)
+; CHECK: [[COND:%[0-9]+]] = fcmp ole x86_fp80 %value, 0xK00000000000000000000
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_09 = call x86_fp80 @log2l(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  %call_10 = call x86_fp80 @logbl(x86_fp80 %value)
+; CHECK: [[COND:%[0-9]+]] = fcmp ole x86_fp80 %value, 0xK00000000000000000000
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_10 = call x86_fp80 @logbl(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  %call_11 = call x86_fp80 @log1pl(x86_fp80 %value)
+; CHECK: [[COND:%[0-9]+]] = fcmp ole x86_fp80 %value, 0xKBFFF8000000000000000
+; CHECK: br i1 [[COND]], label %[[CALL_LABEL:cdce.call[0-9]*]], label %[[END_LABEL:cdce.end[0-9]*]], !prof ![[BRANCH_WEIGHT]]
+; CHECK: [[CALL_LABEL]]:
+; CHECK-NEXT: %call_11 = call x86_fp80 @log1pl(x86_fp80 %value)
+; CHECK-NEXT: br label %[[END_LABEL]]
+; CHECK: [[END_LABEL]]:
+
+  ret void
+}
+
+declare x86_fp80 @acosl(x86_fp80)
+declare x86_fp80 @asinl(x86_fp80)
+declare x86_fp80 @cosl(x86_fp80)
+declare x86_fp80 @sinl(x86_fp80)
+declare x86_fp80 @acoshl(x86_fp80)
+declare x86_fp80 @sqrtl(x86_fp80)
+declare x86_fp80 @atanhl(x86_fp80)
+declare x86_fp80 @logl(x86_fp80)
+declare x86_fp80 @log10l(x86_fp80)
+declare x86_fp80 @log2l(x86_fp80)
+declare x86_fp80 @logbl(x86_fp80)
+declare x86_fp80 @log1pl(x86_fp80)
+
+; CHECK: ![[BRANCH_WEIGHT]] = !{!"branch_weights", i32 1, i32 2000}