Convert fcmp with 0.0 from casted integers to icmp

This is already handled in general when it is known the
conversion can't lose bits with smaller integer types
casted into wider floating point types.

This pattern happens somewhat often in GPU programs that cast
workitem intrinsics to float, which are often compared with 0.

Specifically handle the special case of compares with zero which
should also be known to not lose information. I had a more general
version of this which allows equality compares if the casted float is
exactly representable in the integer, but I'm not 100% confident that
is always correct.

Also fold cases that aren't integers to true / false.

llvm-svn: 225265

1 files changed, 454 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/cast-int-fcmp-eq-0.ll b/llvm/test/Transforms/InstCombine/cast-int-fcmp-eq-0.ll
new file mode 100644
index 00000000000..551d0efce5e
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/cast-int-fcmp-eq-0.ll
@@ -0,0 +1,454 @@
+; RUN: opt -S -instcombine < %s | FileCheck %s
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_0_uitofp(
+; CHECK-NEXT: icmp eq i32 %i, 0
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_oeq_int_0_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_n0_uitofp(
+; CHECK: uitofp
+; CHECK: fcmp oeq
+define i1 @i32_cast_cmp_oeq_int_n0_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp oeq float %f, -0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_0_sitofp(
+; CHECK-NEXT: icmp eq i32 %i, 0
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_oeq_int_0_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_n0_sitofp(
+; CHECK: sitofp
+; CHECK: fcmp oeq
+define i1 @i32_cast_cmp_oeq_int_n0_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp oeq float %f, -0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_one_int_0_uitofp(
+; CHECK-NEXT: icmp ne i32 %i, 0
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_one_int_0_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp one float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_one_int_n0_uitofp(
+; CHECK: uitofp
+; CHECK: fcmp one
+define i1 @i32_cast_cmp_one_int_n0_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp one float %f, -0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_one_int_0_sitofp(
+; CHECK-NEXT: icmp ne i32 %i, 0
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_one_int_0_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp one float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_one_int_n0_sitofp(
+; CHECK: sitofp
+; CHECK: fcmp one
+define i1 @i32_cast_cmp_one_int_n0_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp one float %f, -0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_ueq_int_0_uitofp(
+; CHECK-NEXT: icmp eq i32 %i, 0
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_ueq_int_0_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp ueq float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_ueq_int_n0_uitofp(
+; CHECK: uitofp
+; CHECK: fcmp ueq
+define i1 @i32_cast_cmp_ueq_int_n0_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp ueq float %f, -0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_ueq_int_0_sitofp(
+; CHECK-NEXT: icmp eq i32 %i, 0
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_ueq_int_0_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp ueq float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_ueq_int_n0_sitofp(
+; CHECK: sitofp
+; CHECK: fcmp ueq
+define i1 @i32_cast_cmp_ueq_int_n0_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp ueq float %f, -0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_une_int_0_uitofp(
+; CHECK-NEXT: icmp ne i32 %i, 0
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_une_int_0_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp une float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_une_int_n0_uitofp(
+; CHECK: uitofp
+; CHECK: fcmp une
+define i1 @i32_cast_cmp_une_int_n0_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp une float %f, -0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_une_int_0_sitofp(
+; CHECK-NEXT: icmp ne i32 %i, 0
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_une_int_0_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp une float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_une_int_n0_sitofp(
+; CHECK: sitofp
+; CHECK: fcmp une
+define i1 @i32_cast_cmp_une_int_n0_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp une float %f, -0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_ogt_int_0_uitofp(
+; CHECK: icmp ne i32 %i, 0
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_ogt_int_0_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp ogt float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_ogt_int_n0_uitofp(
+; CHECK: uitofp
+; CHECK: fcmp ogt
+define i1 @i32_cast_cmp_ogt_int_n0_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp ogt float %f, -0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_ogt_int_0_sitofp(
+; CHECK: icmp sgt i32 %i, 0
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_ogt_int_0_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp ogt float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_ogt_int_n0_sitofp(
+; CHECK: sitofp
+; CHECK: fcmp ogt
+define i1 @i32_cast_cmp_ogt_int_n0_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp ogt float %f, -0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_ole_int_0_uitofp(
+; CHECK: icmp eq i32 %i, 0
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_ole_int_0_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp ole float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_ole_int_0_sitofp(
+; CHECK: icmp slt i32 %i, 1
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_ole_int_0_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp ole float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_olt_int_0_uitofp(
+; CHECK: ret i1 false
+define i1 @i32_cast_cmp_olt_int_0_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp olt float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_olt_int_0_sitofp(
+; CHECK: icmp slt i32 %i, 0
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_olt_int_0_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp olt float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i64_cast_cmp_oeq_int_0_uitofp(
+; CHECK-NEXT: icmp eq i64 %i, 0
+; CHECK-NEXT: ret
+define i1 @i64_cast_cmp_oeq_int_0_uitofp(i64 %i) {
+  %f = uitofp i64 %i to float
+  %cmp = fcmp oeq float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i64_cast_cmp_oeq_int_0_sitofp(
+; CHECK-NEXT: icmp eq i64 %i, 0
+; CHECK-NEXT: ret
+define i1 @i64_cast_cmp_oeq_int_0_sitofp(i64 %i) {
+  %f = sitofp i64 %i to float
+  %cmp = fcmp oeq float %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i64_cast_cmp_oeq_int_0_uitofp_half(
+; CHECK-NEXT: icmp eq i64 %i, 0
+; CHECK-NEXT: ret
+define i1 @i64_cast_cmp_oeq_int_0_uitofp_half(i64 %i) {
+  %f = uitofp i64 %i to half
+  %cmp = fcmp oeq half %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i64_cast_cmp_oeq_int_0_sitofp_half(
+; CHECK-NEXT: icmp eq i64 %i, 0
+; CHECK-NEXT: ret
+define i1 @i64_cast_cmp_oeq_int_0_sitofp_half(i64 %i) {
+  %f = sitofp i64 %i to half
+  %cmp = fcmp oeq half %f, 0.0
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_0_uitofp_ppcf128(
+; CHECK: uitofp
+; CHECK: fcmp oeq
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_oeq_int_0_uitofp_ppcf128(i32 %i) {
+  %f = uitofp i32 %i to ppc_fp128
+  %cmp = fcmp oeq ppc_fp128 %f, 0xM00000000000000000000000000000000
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_i24max_uitofp(
+; CHECK: uitofp
+; CHECK: fcmp oeq
+
+; XCHECK: icmp eq i32 %i, 16777215
+; XCHECK-NEXT: ret
+define i1 @i32_cast_cmp_oeq_int_i24max_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0x416FFFFFE0000000
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_i24max_sitofp(
+; CHECK: sitofp
+; CHECK: fcmp oeq
+
+; XCHECK: icmp eq i32 %i, 16777215
+; XCHECK-NEXT: ret
+define i1 @i32_cast_cmp_oeq_int_i24max_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0x416FFFFFE0000000
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_i24maxp1_uitofp(
+; CHECK: uitofp
+; CHECK: fcmp oeq
+
+; XCHECK: icmp eq i32 %i, 16777216
+; XCHECK-NEXT: ret
+define i1 @i32_cast_cmp_oeq_int_i24maxp1_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0x4170000000000000
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_i24maxp1_sitofp(
+; CHECK: sitofp
+; CHECK: fcmp oeq
+
+; XCHECK: icmp eq i32 %i, 16777216
+; XCHECK-NEXT: ret
+define i1 @i32_cast_cmp_oeq_int_i24maxp1_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0x4170000000000000
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_i32umax_uitofp(
+; CHECK: uitofp
+; CHECK: fcmp oeq
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_oeq_int_i32umax_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0x41F0000000000000
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_i32umax_sitofp(
+; CHECK: sitofp
+; CHECK: fcmp oeq
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_oeq_int_i32umax_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0x41F0000000000000
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_i32imin_uitofp(
+; CHECK: uitofp
+; CHECK: fcmp oeq
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_oeq_int_i32imin_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0xC1E0000000000000
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_i32imin_sitofp(
+; CHECK: sitofp
+; CHECK: fcmp oeq
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_oeq_int_i32imin_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0xC1E0000000000000
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_i32imax_uitofp(
+; CHECK: uitofp
+; CHECK: fcmp oeq
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_oeq_int_i32imax_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0x41E0000000000000
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_i32imax_sitofp(
+; CHECK: sitofp
+; CHECK: fcmp oeq
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_oeq_int_i32imax_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0x41E0000000000000
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_negi32umax_uitofp(
+; CHECK: uitofp
+; CHECK: fcmp oeq
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_oeq_int_negi32umax_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0xC1F0000000000000
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_int_negi32umax_sitofp(
+; CHECK: sitofp
+; CHECK: fcmp oeq
+; CHECK-NEXT: ret
+define i1 @i32_cast_cmp_oeq_int_negi32umax_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0xC1F0000000000000
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_half_uitofp(
+; CHECK: ret i1 false
+define i1 @i32_cast_cmp_oeq_half_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0.5
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_oeq_half_sitofp(
+; CHECK: ret i1 false
+define i1 @i32_cast_cmp_oeq_half_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp oeq float %f, 0.5
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_one_half_uitofp(
+; CHECK: ret i1 true
+define i1 @i32_cast_cmp_one_half_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp one float %f, 0.5
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_one_half_sitofp(
+; CHECK: ret i1 true
+define i1 @i32_cast_cmp_one_half_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp one float %f, 0.5
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_ueq_half_uitofp(
+; CHECK: ret i1 false
+define i1 @i32_cast_cmp_ueq_half_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp ueq float %f, 0.5
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_ueq_half_sitofp(
+; CHECK: ret i1 false
+define i1 @i32_cast_cmp_ueq_half_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp ueq float %f, 0.5
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_une_half_uitofp(
+; CHECK: ret i1 true
+define i1 @i32_cast_cmp_une_half_uitofp(i32 %i) {
+  %f = uitofp i32 %i to float
+  %cmp = fcmp une float %f, 0.5
+  ret i1 %cmp
+}
+
+; CHECK-LABEL: @i32_cast_cmp_une_half_sitofp(
+; CHECK: ret i1 true
+define i1 @i32_cast_cmp_une_half_sitofp(i32 %i) {
+  %f = sitofp i32 %i to float
+  %cmp = fcmp une float %f, 0.5
+  ret i1 %cmp
+}